RTX 2080 short or something else?

MSIGamer72

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So I've got an ASUS ROG Strix 2080 that doesn't work. The LEDs on the housing come on but there are no other signs of life and I thought this GPU would make a good project to learn electronic repair - I've been trying to get into this for some time.

I could really use some help as I think I'm hitting the ceiling of what I know (very little) about electronics.

As far as I can see, there are no physical signs of component damage, and whilst the card LEDs do turn on, the fans don't spin and I'm not able to POST. The GPU does not get warm so that's somewhat reassuring.

So far I've been able to determine that none of the 12V rails are shorted to ground nor to Vcore or Vmem. There are no boardview type images/documents I can rely on for identifying rails, but an initial voltage test revealed 12V coming through to three inductors on the right side of the board (labelled) as well as the bottom left, as well as 3.3V in the bottom left. 5V were identified at the top (labelled), and one of the inductors appears to short to ground (approx. 0.2-0.4 ohms).

The part I'm not so proud of... after a long exam today I decided I would come home and jup right into diagnostics... and that's where things went a bit sideways. I tried measuring across a small capacitor (don't ask why I thought this was a good idea) and ended up touching another component (a resistor I think) at the same time. This caused the PCI-e extender ribbon to smoke (I ended up burning the first two pins (12V) on the back and front of this ribbon. I used a riser cable as my current tower isn't large enough to house the bare GPU and try to test voltages etc very well simultaneously.

There's no identifiable damage on the GPU pcb. I decided to hook the GPU up to the motherboard directly, and the PC would no longer start. Knowing I probably shouldn't, I tried to restart the computer which caused a spark across what appears to be a sense resistor adjacent to one of the Vcore phases - nothing else appears to have changed with the GPU in terms of shorts to ground (the original unidentified power rail is still shorted to ground) and there doesn't appear to be any 12V shorts to the Vcore either. I've got a new Corsair RM850 so i'm hoping it kicked in quick enough to prevent any serious damage to the board.

I haven't connected power since in case it burns the card outright, and I'm having difficulty narrowing the potential original short to the potentially culprit component (I'm hoping it's not a short within the PCB) as well as trying to figure out if I've now introduced a new problem (I suspect it is related to the 12V power supply from the PCI-e as that was what was blown on the riser cable I was using).
I can't seem to find any datasheet about the powerstations/MOSFETs to know where I should be testing and my current attempt at trying to hot air the one off the board closest to the sense resistor that blew hasn't been successful (I will try again tomorrow).

I feel like there's more testing to be done before I completely throw in the towel, and with any luck my little mishap hasn't caused any irreversible damage. Any ideas where to go from here?
 

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“Any ideas where to go from here?”

To the store to get another card, fire extinguisher, and an electrical engineering book.

This is well above my pay grade but my guess is that when you shorted the resistor it may have damaged a PCB trace which is now causing it to spark. I had that happen once. If the power got dumped into the VRM, then you may have fried the chip itself. But I’m guessing here. We need one of [H] engineers to give you a good answer.
 
Thanks, to be honest this is more of a learning thing for me at this stage, and we're still probably several months away from reasonably priced and available GPUs.

I am a bit worried about power getting dumped into the VRM as you said, I thought I'd find a short circuit to verify this, but all 12V rails show decent resistance to the VRMs so I have to assume there's no short directly to the VRMs.

I'm tempted to run power to the minor rails and check for voltage dropoff...not so keen on running power to ay 12V rails just yet.

The resistor that blew appears to be a shunt resistor...I can't quite figure why it would blow as if there's a short when there's no identifiable short from the PCI-e 12 V rail that appeared to be the source as evidenced by the damaged 12 V PCB traces on the riser cable when my mishap occurred.
 
I have some experience with repairing graphics cards.

If the system won't power on at all with this card plugged in, you have a short to ground. You said you don't have a short on the 8 pin connectors, so that leaves the 12V input from the PCI-E slot. Check for a short to ground on pin 2 of the slot connector.

The shunt at the bottom of the card that your picture says is "smoked" is most likely wired up to the 12V input from the slot. You will need to figure out where the short is in that circuit. It's hard to say without the card in my hands to test, but if it was shorted for long enough to visibly damage a PCI-E riser, chances are that the damage is actually in the 12V power plane itself, which means the card is beyond saving. Nevertheless, it would be worth removing the suspect shunt and checking to see if that clears the short. If it does, then there's a chance the damage is a component situated between the shunt and ground, such as a power stage or a capacitor.

Also, do not use short detection ("beep") mode when troubleshooting. There are circuits on this card (such as the core and main memory power) that measure as only a few milliohms to ground by design. The core should measure about 300 mohms, as I recall, and the memory should be maybe 10-15 ohms. Both of these are well below the threshold that most multimeters consider to be a short. The proper way to check for short circuits on a graphics card is to use regular ohms mode, and compare your readings to the known-good values.

The thing I would do next is remove that shunt, and see if that clears the short on pin 2 of the PCI-E connector. Do you have access to hot air? Do not attempt to use a soldering iron.
 
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I have some experience with repairing graphics cards.

If the system won't power on at all with this card plugged in, you have a short to ground. You said you don't have a short on the 8 pin connectors, so that leaves the 12V input from the PCI-E slot. Check for a short to ground on pin 2 of the slot connector.

The shunt at the bottom of the card that your picture says is "smoked" is most likely wired up to the 12V input from the slot. You will need to figure out where the short is in that circuit. It's hard to say without the card in my hands to test, but if it was shorted for long enough to visibly damage a PCI-E riser, chances are that the damage is actually in the 12V power plane itself, which means the card is beyond saving. Nevertheless, it would be worth removing the suspect shunt and checking to see if that clears the short. If it does, then there's a chance the damage is a component situated between the shunt and ground, such as a power stage or a capacitor.

Also, do not use short detection ("beep") mode when troubleshooting. There are circuits on this card (such as the core and main memory power) that measure as only a few milliohms to ground by design. The core should measure about 300 mohms, as I recall, and the memory should be maybe 10-15 ohms. Both of these are well below the threshold that most multimeters consider to be a short. The proper way to check for short circuits on a graphics card is to use regular ohms mode, and compare your readings to the known-good values.

The thing I would do next is remove that shunt, and see if that clears the short on pin 2 of the PCI-E connector. Do you have access to hot air? Do not attempt to use a soldering iron.
You're being too modest...I've read your posts and seen one of your YouTube vids.

Thanks for the advice. I'll have to check properly this weekend as I'm on nights this week (I'm a doctor by trade). I did manage to remove the resistor with hot air and there appears to be several kilo ohms of resistance between pin 2 and just one of the resistor pads.

I will upload proper details and pics later this week when I can finally sit down and figure this out. From what I can see, the resistor is located near some vias, which have two small capacitors before them. This makes me think the resistor comes before the power stages. Is it reasonable to assume this or would a sense resistor generally come after a power stage rather than directly from the 12v plane?

I'm not able to detect a short in the two capacitors I removed when checking resistance nor when using short detection mode. I'm probably going about it wrong.
 
You're being too modest...I've read your posts and seen one of your YouTube vids.

Thanks for the advice. I'll have to check properly this weekend as I'm on nights this week (I'm a doctor by trade). I did manage to remove the resistor with hot air and there appears to be several kilo ohms of resistance between pin 2 and just one of the resistor pads.

I will upload proper details and pics later this week when I can finally sit down and figure this out. From what I can see, the resistor is located near some vias, which have two small capacitors before them. This makes me think the resistor comes before the power stages. Is it reasonable to assume this or would a sense resistor generally come after a power stage rather than directly from the 12v plane?

I'm not able to detect a short in the two capacitors I removed when checking resistance nor when using short detection mode. I'm probably going about it wrong.
When you say you removed the resistor, do you mean the shunt?

Assuming yes, you should see the following on a healthy card:
Right side of shunt -> PCI-E Pin 2 : 0 ohms
Left side of shunt -> PCI-E Pin 2: Thousands or more
Right side of shunt -> Ground: Thousands or more
Left side of shutnt -> Ground: Thousands

If you mean the tiny 0402 resistor you said you were probing when you bridged something you shouldn't have, don't worry about that area for now. You need to figure out what general part of the board your dead short to ground is in first.
 
When you say you removed the resistor, do you mean the shunt?

Assuming yes, you should see the following on a healthy card:
Right side of shunt -> PCI-E Pin 2 : 0 ohms
Left side of shunt -> PCI-E Pin 2: Thousands or more
Right side of shunt -> Ground: Thousands or more
Left side of shutnt -> Ground: Thousands

If you mean the tiny 0402 resistor you said you were probing when you bridged something you shouldn't have, don't worry about that area for now. You need to figure out what general part of the board your dead short to ground is in first.
Yes I meant the R005 shunt not the resistor I accidentally probed.

Right side of shunt to pin 2 - 0.6 ohms
Left side of shunt to pin 2 > 2 MOhm

Right side of shunt to ground > 2MOhm
Left side of shunt to ground - 13.3 kOhm

Regarding the 2MOhm readings, I note they occasionally start rising to 2 MOhm then give me a "1 .", so I'm assuming the resistance is greater than this upper limit of my multimeter.
 
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Yes I meant the R005 shunt not the resistor I accidentally probed.

Right side of shunt to pin 2 - 0.6 ohms
Left side of shunt to pin 2 > 2 MOhm

Right side of shunt to ground > 2MOhm
Left side of shunt to ground - 13.3 kOhm

Regarding the 2MOhm readings, I note they occasionally start rising to 2 MOhm then give me a "1 .", so I'm assuming the resistance is greater than this upper limit of my multimeter.
That all looks healthy. You may have gotten lucky, and not done any actual damage. Maybe.

What resistance do you have on the left side of each of the other shunts? Edit: That is, resistance to ground.
 
That all looks healthy. You may have gotten lucky, and not done any actual damage. Maybe.

What resistance do you have on the left side of each of the other shunts? Edit: That is, resistance to ground.
Shunt at:

J8 adjacent to 12v from PSU
Right = 44 kOhm
Left = 36.7 kOhm

J11 adjacent to 12v from PSU
Right = 9.04 kOhm
Left = 9.24 kOhm

Shunts were still on the board when I took these readings if that changes anything.
 
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Shunt at:

J8 adjacent to 12v from PSU
Right = 44 kOhm
Left = 36.7 kOhm

J11 adjacent to 12v from PSU
Right = 9.04 kOhm
Left = 9.24 kOhm

Shunts were still on the board when I took these readings if that changes anything.
Ideally, you want to take these measurements with the shunts still on the board. The shunts have a very low resistance (typically about 0.5 ohms), and thus don't contribute much to the resistance value.

Your measurements there are all over the place, but still within the realm of normal, so that's a good sign. It does not appear that you have a dead short to ground. If you did, you'd have a really low resistance to ground on one or both of them.

Next, check the resistance through the shunt you removed. You should have about 0.5 ohms. If you have significantly greater than that, you'll need a new one. If not, reinstall it on the board. You can probably get away with using a soldering iron on that one, if it's easier than hot air. Just be quick, and use a good quality flux.

After that, with the card unplugged from the system completely, take resistance measurements between the locations shown in these pictures. (Click to embiggen)
strix_2080_low_voltage_resistance_checks.jpg

Here's what I suspect each one is:
1. Memory Power - expected resistance is something like 15-30 ohms
2. GPU Core Power - expected resistance is ~300 milliohms
3. 5V? - I'd guess about 2K ohms expected
4. ~1V? - I'd guess about 3500 ohms
5. 5V for usb-c? - Resistance should probably be a few K
6. 3.3V? - You usually see 200-400 ohms on this

Each one of those locations is the output of a power supply circuit. By checking the resistance on each one, we're checking to see if a short circuit has formed either through the load or some part of the power supply. If either of those things had happened, that would explain why our card doesn't work. I may be wrong about which one of the ones with question marks is which, which is part of the reason we're doing these checks. We need to at least kind of know what each one does before we do the next step.

Edit: When taking your resistance measurements, don't be afraid to scrape at the solder connections a little, in order to get a solid connection with your probes. You'll sometimes get a layer of oxidation on top of the solder, which throws your resistance measurements off, and you have to scrape through it to get accurate readings. Obviously, just be careful not to knock any of the tiny components off the board. You won't damage any of the big ones doing this.
 
Ideally, you want to take these measurements with the shunts still on the board. The shunts have a very low resistance (typically about 0.5 ohms), and thus don't contribute much to the resistance value.

Your measurements there are all over the place, but still within the realm of normal, so that's a good sign. It does not appear that you have a dead short to ground. If you did, you'd have a really low resistance to ground on one or both of them.

Next, check the resistance through the shunt you removed. You should have about 0.5 ohms. If you have significantly greater than that, you'll need a new one. If not, reinstall it on the board. You can probably get away with using a soldering iron on that one, if it's easier than hot air. Just be quick, and use a good quality flux.

After that, with the card unplugged from the system completely, take resistance measurements between the locations shown in these pictures. (Click to embiggen)
View attachment 328712

Here's what I suspect each one is:
1. Memory Power - expected resistance is something like 15-30 ohms
2. GPU Core Power - expected resistance is ~300 milliohms
3. 5V? - I'd guess about 2K ohms expected
4. ~1V? - I'd guess about 3500 ohms
5. 5V for usb-c? - Resistance should probably be a few K
6. 3.3V? - You usually see 200-400 ohms on this

Each one of those locations is the output of a power supply circuit. By checking the resistance on each one, we're checking to see if a short circuit has formed either through the load or some part of the power supply. If either of those things had happened, that would explain why our card doesn't work. I may be wrong about which one of the ones with question marks is which, which is part of the reason we're doing these checks. We need to at least kind of know what each one does before we do the next step.

Edit: When taking your resistance measurements, don't be afraid to scrape at the solder connections a little, in order to get a solid connection with your probes. You'll sometimes get a layer of oxidation on top of the solder, which throws your resistance measurements off, and you have to scrape through it to get accurate readings. Obviously, just be careful not to knock any of the tiny components off the board. You won't damage any of the big ones doing this.
The shunt measured around 0.4 ohms, and it's now back on the board.

1 - 1.0 ohm
2 - 0.9 ohms
3 - 14.8 kOhms
4 - 3.12 kOhms
5 - 81.8 kOhms
6 - 10.2 ohms

Edit: before my probing incident, the ohms from Vmem to ground were in the 20's, so the 1 ohm appears to be new.

EDIT #2: ignore the above comment as I cannot confirm since I didn't write it down.

Also point 3 had measured at 5V before.
 
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The shunt measured around 0.4 ohms, and it's now back on the board.

1 - 1.0 ohm
2 - 0.9 ohms
3 - 14.8 kOhms
4 - 3.12 kOhms
5 - 81.8 kOhms
6 - 10.2 ohms

Edit: before my probing incident, the ohms from Vmem to ground were in the 20's, so the 1 ohm appears to be new.

Also point 3 had measured at 5V before.
#1 is your problem. 1.0 ohms is basically a dead short to ground on that rail. I went and looked at some footage I took when I repaired an EVGA reference 2080 (which I'm using to type this post :cool: ), and I got 55 ohms on the memory rail on that card.

Your next step is to figure out what component is in short, and replace it. Unfortunately, this is likely to be pretty tough, unless you have some elaborate equipment. Probably 40% of the components on the board are related to the memory rail, and your short could be in almost any of them, including the memory ICs or the GPU die itself.

There are a few ways of going about this:

* You may get lucky, and figure out which components are damaged with a closer visual inspection. You mentioned you're a doctor - if you have access to a stereo microscope at work, you might try using it to examine the board.
* Plug the card into power and use a thermal camera, isopropanol, or your fingers to look for components that get hot.
* Attach a bench power supply to the memory rail, and inject voltage (it's designed for 1.35 volts), and look for components that get hot
* Speculatively remove components until you find the short.

If you strike out with the visual inspection and voltage injection, it might be worth at least removing the memory rail power stages. Just be aware that if you can clear the short by removing them, you'll likely need a board preheater and a great deal of luck to get new ones soldered on properly.
 
#1 is your problem. 1.0 ohms is basically a dead short to ground on that rail. I went and looked at some footage I took when I repaired an EVGA reference 2080 (which I'm using to type this post :cool: ), and I got 55 ohms on the memory rail on that card.

Your next step is to figure out what component is in short, and replace it. Unfortunately, this is likely to be pretty tough, unless you have some elaborate equipment. Probably 40% of the components on the board are related to the memory rail, and your short could be in almost any of them, including the memory ICs or the GPU die itself.

There are a few ways of going about this:

* You may get lucky, and figure out which components are damaged with a closer visual inspection. You mentioned you're a doctor - if you have access to a stereo microscope at work, you might try using it to examine the board.
* Plug the card into power and use a thermal camera, isopropanol, or your fingers to look for components that get hot.
* Attach a bench power supply to the memory rail, and inject voltage (it's designed for 1.35 volts), and look for components that get hot
* Speculatively remove components until you find the short.

If you strike out with the visual inspection and voltage injection, it might be worth at least removing the memory rail power stages. Just be aware that if you can clear the short by removing them, you'll likely need a board preheater and a great deal of luck to get new ones soldered on properly.
Ahh shucks. A microscope will be out of the question, the labs are swamped right now with this pandemic. I did use a pair of magnifying glasses I have lying around to do an inspection a couple weeks back, and there was no obvious damage.

I've got a power bench supply at home, I could try and inject voltage to see if this heats up any components. Where exactly would I apply voltage to? And would you say 2 amps is the max current I should allow that rail to draw during testing? (I see a lot of people setting 2 amps as their go to current draw limit).

And when the pc wouldn't turn on after the probing mishap, the shunt sparked on a subsequent attempt. If I now plug my GPU into the motherboard, how can I be sure that this won't cause it to happen again and potentially cause permanent damage?

If you wouldn't mind posting the link to that repair video it might be useful for reference.

I haven't connected one of the small capacitors below the shunt back to the board yet (the smaller one closest to the shunt) as I seemed to have misplaced it 😅. if I don't find it in my work area, do you reckon it would have a significant impact on function?

Thanks for all your input so far, looks like I've got some testing to do. If I find anything, I'll post back in here.

Edit: don't mind about the video, I thought you meant a video online not one you did yourself... probably not as useful for me without commentary.
 
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#1 is your problem. 1.0 ohms is basically a dead short to ground on that rail. I went and looked at some footage I took when I repaired an EVGA reference 2080 (which I'm using to type this post :cool: ), and I got 55 ohms on the memory rail on that card.

Your next step is to figure out what component is in short, and replace it. Unfortunately, this is likely to be pretty tough, unless you have some elaborate equipment. Probably 40% of the components on the board are related to the memory rail, and your short could be in almost any of them, including the memory ICs or the GPU die itself.

There are a few ways of going about this:

* You may get lucky, and figure out which components are damaged with a closer visual inspection. You mentioned you're a doctor - if you have access to a stereo microscope at work, you might try using it to examine the board.
* Plug the card into power and use a thermal camera, isopropanol, or your fingers to look for components that get hot.
* Attach a bench power supply to the memory rail, and inject voltage (it's designed for 1.35 volts), and look for components that get hot
* Speculatively remove components until you find the short.

If you strike out with the visual inspection and voltage injection, it might be worth at least removing the memory rail power stages. Just be aware that if you can clear the short by removing them, you'll likely need a board preheater and a great deal of luck to get new ones soldered on properly.
So I've finally had time this past weekend to get back to working on this card.

First, regarding point 1 you asked me to measure before, I was measuring to the ground pin on the capacitor so was reading resistance to ground. Resistance to the positive pin of the capacitor measures 25.6 ohms, which sounds about right.

Also, I have managed to diagnose and replace a shorted mosfet (the very bottom one) after my previous mishap using the alcohol trick (it was drying in the bottom left corner), and today I can say I have been able to power up PC again with the card installed as before without any component getting smoked and the computer shutting down :cool:.

The power rails on the right of the card all read around 12 V. On the left side of the card, the inductor at the top reads around 5 V. There are no voltage readings at the remaining inductors on the left side.

If you're still interested in helping me finally get to the bottom of the original problem, I'm all ears!

Thanks again.
 
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So I've finally had time this past weekend to get back to working on this card.

First, regarding point 1 you asked me to measure before, I was measuring to the ground pin on the capacitor so was reading resistance to ground. Resistance to the positive pin of the capacitor measures 25.6 ohms, which sounds about right.

Also, I have managed to diagnose and replace a shorted mosfet (the very bottom one) after my previous mishap using the alcohol trick (it was drying in the bottom left corner), and today I can say I have been able to power up PC again with the card installed as before without any component getting smoked and the computer shutting down :cool:.

The power rails on the right of the card all read around 12 V. On the left side of the card, the inductor at the top reads around 5 V. There are no voltage readings at the remaining inductors on the left side.

If you're still interested in helping me finally get to the bottom of the original problem, I'm all ears!

Thanks again.
Regarding #1, I realized after reading your post that I marked the wrong terminal on that capacitor. 25.6 ohms is totally sane for the memory rail resistance. This is actually a relief - my results trying to find a dead short on the memory power rail are pretty poor.

Anyway, I'm not totally sure we're speaking the same language, so let's just confirm those voltage readings. What voltage are you reading between each of these points and ground with the system powered on?
front_voltage_readings.jpg

It sounds like you have 12V in at all the places you should, and that it's just the lower voltage rails that aren't running for some reason. To troubleshoot those, you'll need to check for all the input voltages at each controller IC until you find one that has all the proper inputs (usually power and enable), but isn't running, and then you troubleshoot that circuit.
 
Regarding #1, I realized after reading your post that I marked the wrong terminal on that capacitor. 25.6 ohms is totally sane for the memory rail resistance. This is actually a relief - my results trying to find a dead short on the memory power rail are pretty poor.

Anyway, I'm not totally sure we're speaking the same language, so let's just confirm those voltage readings. What voltage are you reading between each of these points and ground with the system powered on?
View attachment 337161

It sounds like you have 12V in at all the places you should, and that it's just the lower voltage rails that aren't running for some reason. To troubleshoot those, you'll need to check for all the input voltages at each controller IC until you find one that has all the proper inputs (usually power and enable), but isn't running, and then you troubleshoot that circuit.
Thanks, I wasn't too keen on trying to find the short on memory rail either as like you said it seemed to go to a lot of places on the board, so I'm very relieved as well!

Okay so here's what I have for the inductors you labelled in the above pic.

1 - 12.05 V
2 - 12.05 V
3 - 12.04 V
4 - 0 V
5 - 0 V
6 - 0 V
7 - 4.998 V
8 - 0.025 V
9 - 0 V
10 - 0.019 V

I've struggled to find datasheets for two of the controllers, BFRJ (next to inductor labelled 7 on the pic) and BFDJ (next to inductor 10).

I've been able to deduce that:
i. BFRJ is MP28168GQ
ii. BFDJ is MP8858GQ
- again no actual datasheets have been found.

Controllers voltages are as follows:

BFRJ (inductor 7) - unsure of pinout but I'm hoping you'll be able to make sense of it
1 - 12.05 V
2 - 0 V (ground)
3 - 0 V (ground)
4 - 3.603 V
5 - 0 V (ground)
6 - 0 V (ground)
7 - 0.058 V
8 - 3.314 V
9 - 3.606 V
10 - 0 V (ground)
11 - 0 V (ground)
12 - 0 V
13 - 8.06 V
14 - 4.996 V
15 - 5.002 V
16 - 8.48 V

M8633A (inductor 8)
8 (enable) - 0 v
9 (pgood) - 0.024 v
10, 21 (Vin) - 12.05 V

M8633a (inductor 9)
8 (enable) - 0 v
9 (pgood) - 0 v
10, 21 (Vin) - 12.05 V

BFDJ (inductor 10) - I initially tried to estimate which pin enable, pgood and Vout come from based on a similar datasheet (MP8864) but because MP8864 only has 15 pins I haven't relied on it.

1 - 12.06 V
2 - 0 V (ground)
3 - 0 V (ground)
4 - 0 V
5 - 0.025 V
6 - 0.024 V
7 - 0 V
8 - 0.024 V
9 - 0 V
10 - 0 V (ground)
11 - 0 V (ground)
12 - 0 V
13 - 0.039 V
14 - 0 V
15 - 0 V
16 - 0.029 V

It would seem as though the short/problem exists on/around/after the circuit involving BFRJ/inductor 7 which appears to be a 5 V rail.

Look forward to hearing your thoughts.

Thanks again.

EDIT: I've added pics of the controller ICs if if helps at all. I have alot of pics so if you think pics of any areas will help, let me know.

EDIT 2: I've gone ahead and added which pins on BFRJ and BFDJ measured to ground (whether these are actually grounds or shorts I cannot say). Hopefully this will help rule pins out to deduce pinout.

EDIT 3: I've tried checking for continuity between each of the pins on BFRJ that showed voltage and the pins of the other 3 controller ICs, but haven't found any obvious connection.
 

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Something that occurs to me is that you don't seem to have a 3.3V rail. There's what appears to be a 0 ohm resistor on the back of the card near the PCI-E connector - see what that's connected to, and what the voltage on each side of it is.

The controller ICs, like those MP8633As, often run on 3.3V, so if the 3.3V rail is dead for some reason, that would explain why nothing works.
 
Something that occurs to me is that you don't seem to have a 3.3V rail. There's what appears to be a 0 ohm resistor on the back of the card near the PCI-E connector - see what that's connected to, and what the voltage on each side of it is.

The controller ICs, like those MP8633As, often run on 3.3V, so if the 3.3V rail is dead for some reason, that would explain why nothing works.
This resistor here? I'll check in the morning and report back.
 

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Something that occurs to me is that you don't seem to have a 3.3V rail. There's what appears to be a 0 ohm resistor on the back of the card near the PCI-E connector - see what that's connected to, and what the voltage on each side of it is.

The controller ICs, like those MP8633As, often run on 3.3V, so if the 3.3V rail is dead for some reason, that would explain why nothing works.
I've gone ahead and checked the resistor - 3.3v either side, 0 ohm approx.

Pics 1 & 2 - checking for continuity - the component on back of board shows continuity to a component on front of board (pin showing continuity is not the same pin as shows continuity with the resistor).

Pics 3 & 4 - up-close of the components showing continuity.

Pic 5 - may have gone a bit overboard here, but I tried to map out some of the 3.3v and 5v areas around the component showing continuity (as well as some 12v and peculiar voltage readings) in case you find this useful at all. 3.3v marked in yellow, 5v marked in red, 12v in blue.

Thanks.
 

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I've gone ahead and checked the resistor - 3.3v either side, 0 ohm approx.

Pics 1 & 2 - checking for continuity - the component on back of board shows continuity to a component on front of board (pin showing continuity is not the same pin as shows continuity with the resistor).

Pics 3 & 4 - up-close of the components showing continuity.

Pic 5 - may have gone a bit overboard here, but I tried to map out the 3.3v and 5v areas I could test (as well as some 12v and lower voltages) in case you found this useful at all.

Thanks.
In the 5th picture, are the terminals marked in yellow all connected together, and the ones marked in red are also connected together?
 
In the 5th picture, are the terminals marked in yellow all connected together, and the ones marked in red are also connected together?
I'll have to test more on 5v, but here's what I have so far.
 

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I'll have to test more on 5v, but here's what I have so far.
Not much more luck with 5V so far, but have updated the 3.3 v connections. Not sure how helpful it is. For the most that area seems connected up. Not really sure where to go from there though. (I've marked some lines pink because I don't actually get 3.3v there but it's connected via the components).

Is it worth going from the Vcc pin on one of the MP8633A controllers to see where it would be getting power from? Or would you know where to check its' power supply?

Cheers.
 

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Not much more luck with 5V so far, but have updated the 3.3 v connections. Not sure how helpful it is. For the most that area seems connected up. Not really sure where to go from there though. (I've marked some lines pink because I don't actually get 3.3v there but it's connected via the components).

Is it worth going from the Vcc pin on one of the MP8633A controllers to see where it would be getting power from? Or would you know where to check its' power supply?

Cheers.
So, the pink lines represent traces that are connecting those terminals, (and you can confirm they're actually connected with a meter), but you have 0V on them with the system powered on?
 
So, the pink lines represent traces that are connecting those terminals, (and you can confirm they're actually connected with a meter), but you have 0V on them with the system powered on?
So voltage wasn't initially checked at pink lines, but showed continuity with system off and GPU on my desk.

I've checked and updated the voltages - some pink lines actually carried 3.3 V and I've changed them to yellow.

Also, the component on the back of the board that received 3.3v from the 0 ohm resistor...the leg connected to this resistor actually connects to a small resistor that carries 3.3V on one end and 0v on the other before the trace disappears into a via. Not sure where this via comes out just yet. Not sure if that changes anything in terms of tracing the 3.3v.
 

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Not sure if this helps or not, but I've been probing around IC MP2888A - the datasheet says it's the multi-phase PWM controller. I thought it might provide a pgood signal to the enable pin on the other ICs on the left hand side but probably not as it controls the VRM phases form what I can gather.

Anyhow, there is no enable or pgood voltage, but VDD18 reads 1.8 V and VDD33 reads 3.3 V - these have nothing to do with enabling the 3.3 and 1.8 V rails do they?

Edit: by the way, I have datasheets for most of the ICs on this card so if you need to take a look at any of them feel free to let me know.
 

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Check each of the controller ICs for its expected Vcc and EN. I'm guessing that what you'll find is most of them have Vcc (probably 3.3V), but En will be missing, like you're seeing with that MP2888A.

You may find that on one of them, you have EN and Vcc, but it's not running. If that's the case, troubleshoot that circuit. If you don't find any that are getting En, then you'll need to figure out where the En signal comes from for each one, and see if any of that circuitry is broken.
 
Check each of the controller ICs for its expected Vcc and EN. I'm guessing that what you'll find is most of them have Vcc (probably 3.3V), but En will be missing, like you're seeing with that MP2888A.

You may find that on one of them, you have EN and Vcc, but it's not running. If that's the case, troubleshoot that circuit. If you don't find any that are getting En, then you'll need to figure out where the En signal comes from for each one, and see if any of that circuitry is broken.

A quick check of the Vcc and EN on the 2 MP8633A chips shows they don't have Vcc or EN.

My only original find with this card was that on the left side of the card, the inductor you marked as 9 showed a short (or what I can only assume is a short). Re-checked it today and it shows 11.7 ohms. I bit the bullet and decided to run some voltage into that inductor. I first started at around 0.6 V with 1 A max current and I think I went to a max of 2 V with 2 A since it didn't seem to pass directly through Vmem or Vcore to the GPU. I can say that there is voltage registered at the capacitors to the right of the 2 Vmem powerstages, with the top one registering approx. the same voltage that I fed in, and the lower one showing about half of this voltage.

I panicked a bit because I could feel what I thought was the GPU die getting warm, even though the "DC" side of the Vmem and Vcore inductors did not show any voltage.

I will have to re-check this tomorrow, but is it possible somehow for a short to exist from inductor 9 directly to the GPU without having to go through the Vcore and/or Vmem pathways?

I'm sure that it was back the of the board that got warm, just off to the left of the die itself on front of the card. I may try the alcohol trick tomorrow with some power supplied. Honestly, I have nothing to lose at this point as I basically have a dead card anyway, but I'm going to try and be as sensible as possible with injecting voltage :dead:

I'll try and trace the origins of the Vcc signals for the 2 MP8633A chips at least, ideally I'd have datasheets for the other two (BFRJ and BFDJ), but I have a feeling they have a similar pinout.

Are you able to make any assumptions regarding where Vcc and EN may be on the BFRJ IC?
 
A quick check of the Vcc and EN on the 2 MP8633A chips shows they don't have Vcc or EN.

My only original find with this card was that on the left side of the card, the inductor you marked as 9 showed a short (or what I can only assume is a short). Re-checked it today and it shows 11.7 ohms. I bit the bullet and decided to run some voltage into that inductor. I first started at around 0.6 V with 1 A max current and I think I went to a max of 2 V with 2 A since it didn't seem to pass directly through Vmem or Vcore to the GPU. I can say that there is voltage registered at the capacitors to the right of the 2 Vmem powerstages, with the top one registering approx. the same voltage that I fed in, and the lower one showing about half of this voltage.

I panicked a bit because I could feel what I thought was the GPU die getting warm, even though the "DC" side of the Vmem and Vcore inductors did not show any voltage.

I will have to re-check this tomorrow, but is it possible somehow for a short to exist from inductor 9 directly to the GPU without having to go through the Vcore and/or Vmem pathways?

I'm sure that it was back the of the board that got warm, just off to the left of the die itself on front of the card. I may try the alcohol trick tomorrow with some power supplied. Honestly, I have nothing to lose at this point as I basically have a dead card anyway, but I'm going to try and be as sensible as possible with injecting voltage :dead:

I'll try and trace the origins of the Vcc signals for the 2 MP8633A chips at least, ideally I'd have datasheets for the other two (BFRJ and BFDJ), but I have a feeling they have a similar pinout.

Are you able to make any assumptions regarding where Vcc and EN may be on the BFRJ IC?
The inductor is in series with the output of the buck converter, so if you applied voltage to its terminals, that's the same as applying voltage to whatever that buck converter powers. I would guess that that buck converter is the PCI-E interface power, which is on the GPU die, so in that sense, you were applying power to the GPU.

Nevertheless, it IS possible to have a short that would connect the output of one buck converter to another, but I don't think that's necessarily what's going on in this case.

Vcc is usually pin 1 or 16 on the two-sided ICs. Look for pins that have voltage. If you have two pins with 3.3V or more on them, and they're not just connected together, chances are one is Vcc and the other En.
 
The inductor is in series with the output of the buck converter, so if you applied voltage to its terminals, that's the same as applying voltage to whatever that buck converter powers. I would guess that that buck converter is the PCI-E interface power, which is on the GPU die, so in that sense, you were applying power to the GPU.

Nevertheless, it IS possible to have a short that would connect the output of one buck converter to another, but I don't think that's necessarily what's going on in this case.

Vcc is usually pin 1 or 16 on the two-sided ICs. Look for pins that have voltage. If you have two pins with 3.3V or more on them, and they're not just connected together, chances are one is Vcc and the other En.
Thanks, I'll check.

Out of curiosity, does the 3.3v enable signal for each of the controller ICs usually have the same source?
 
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