1080 no power to gpu and mem

elior77

n00b
Joined
May 18, 2021
Messages
12
Hey all !

I noticed this forum is a good place for more professional information about diagnosing graphics cards.
I work as an IT manger in a big electronic factory so I have access to all the tools needed.
I have a few cards here I want to fix\learn - I hope it is ok that I share.

This is a 1080 card that was in the oven once...(not by me), current situation is the gpu and mem do not get and voltage.
I can see that the pwm controller (uP9511-on the back) does put out 0.8v for the gpu as far as I understand, I can see the vgpu when starting up go to 0.8v for a brief moment and then go to 0.2v and then 0v

As far as I can tell I did not notice any shorts on the mosfets.

Thanks
Elior

btw I soldered caps where you can see 2 missing caps and replaced the 3rd one.
 

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RazorWind

2[H]4U
Joined
Feb 11, 2001
Messages
3,969
This is a 1080 card that was in the oven once...(not by me), current situation is the gpu and mem do not get and voltage.
I can see that the pwm controller (uP9511-on the back) does put out 0.8v for the gpu as far as I understand, I can see the vgpu when starting up go to 0.8v for a brief moment and then go to 0.2v and then 0v

As far as I can tell I did not notice any shorts on the mosfets.

Thanks
Elior

btw I soldered caps where you can see 2 missing caps and replaced the 3rd one.
After the core VRM shuts down, do you still have the enable signal to the UP9511?
 

RazorWind

2[H]4U
Joined
Feb 11, 2001
Messages
3,969
See if you can locate where the 5V source on the board is, and check to see what you have at the 5VCC pin.

Also check resistance to ground on the output from the 5V regulator.
 

elior77

n00b
Joined
May 18, 2021
Messages
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I think the chip next to the coil that gives 5v reading is the regulator, 8pins but no data sheet,
Marking" 08=E4A", readings:
Pin1: 4.669v
Pin2: 12.1v
Pin3: 5.167v
Pin4: 0v
Pin5: 9.64v
Pin6: 2.156v
Pin7: 5.07v
Pin8: 0.831v

RT8128C Memory voltage regulator:
https://www.richtek.com/assets/product_file/RT8128A=RT8128C/DS8128AC-03.pdf

BOOT, Pin1: 11.55v
UGATE,Pin2: 0v
PGOOD,Pin3: 0v
LGATE/OCSET,Pin4: 0v
VCC,Pin5: 12.09v
FB,Pin6: 0v
EN,Pin7: 0.044v
PHASE,Pin8: 0v
 

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elior77

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May 18, 2021
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The " 08=E4A" is the 5v regulator, and the EN pin gets only 2.1v insted of 3.3v, I lifted the IC and the EN pad puts out 2.1v.
The PCIE is the 3.3v source right ?
What would be a good way to find the root for this 2.1v ?

Thanks !
 

RazorWind

2[H]4U
Joined
Feb 11, 2001
Messages
3,969
The " 08=E4A" is the 5v regulator, and the EN pin gets only 2.1v insted of 3.3v, I lifted the IC and the EN pad puts out 2.1v.
The PCIE is the 3.3v source right ?
What would be a good way to find the root for this 2.1v ?

Thanks !
The 3.3V usually comes from the PCI-E slot connector (second pin from the right in the small part), but some cards actually have a dedicated 3.3V regulator of their own. Check for continuity with the 3.3V pins on the slot connector (refer to the pinout if you need to).

I think you said the 5V rail is running, though, so while the 3.3V rail being low is clearly a problem, it's not a big enough problem for that regulator to not be working.

Check to make sure that the 3.3V rail from the power supply is actually producing 3.3V, and then check for a short on the 3.3V input pins on the card. I suspect you'll find that one of these tests fails.

PS: You sent me an email and I left you hanging. I apologize for that. I've just been busy, but I'll try to respond soon.
 

elior77

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Joined
May 18, 2021
Messages
12
On a few points on the card I do get 3.3v, I assume it indicates the 3.3v supply is ok but it drops to 2.1v for some reason.
Yes, I can get a 5v reading from the regulator.

Pin1: 4.669v
Pin2: 12.1v
Pin3: 5.167v
Pin4: 0v
Pin5: 9.64v
Pin6: 2.156v
Pin7: 5.07v
Pin8: 0.831v

pin3 and pin 7.

I tried replacing the IC with another one and on the first boot I got voltages on the mem and gpu, next boot it went back to 2.1v on the EN pin...

What kind of resistance I expect to see on the 3.3v input pins ?
 
Last edited:

RazorWind

2[H]4U
Joined
Feb 11, 2001
Messages
3,969
On a few points on the card I do get 3.3v, I assume it indicates the 3.3v supply is ok but it drops to 2.1v for some reason.
Yes, I can get a 5v reading from the regulator.

Pin1: 4.669v
Pin2: 12.1v
Pin3: 5.167v
Pin4: 0v
Pin5: 9.64v
Pin6: 2.156v
Pin7: 5.07v
Pin8: 0.831v

pin3 and pin 7.

I tried replacing the IC with another one and on the first boot I got voltages on the mem and gpu, next boot it went back to 2.1v on the EN pin...

What kind of resistance I expect to see on the 3.3v input pins ?
On most cards I've looked at, I see around 350 ohms on the 3.3V rail, but it's not really a rule that that be the case.
 

elior77

n00b
Joined
May 18, 2021
Messages
12
On the 3.3v pin on the PCIE connector (forth pin from the right on the small part) 220K ohm
 
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