Graphics Card Necromancy - Sapphire Radeon R9 390 Nitro


Feb 11, 2001
It's been a while since we've collectively looked at a dead graphics card, but as I'm sure many of you can relate to, the last couple of months have been a real turd sandwich for me, and I just haven't felt like doing this, but that ends today.

I made a mistake uploading the video to Youtube, so I'll have to post that later, but it's coming, for those who prefer the sonorous melody of my voice... ;)

On the bench, we have this handsome Sapphire Radeon R9 390 Nitro, which came to me in the same lot as the 980 Ti we looked at last time. I was kinda stoked to get this card in that lot, as I can't remember ever seeing a 300 series of any kind in person. I gather that almost everyone who might have wanted one already had a 200 series, and was unmoved by the minor improvements these brought to the table.
The seller described the card as totally dead, no fan spin or anything, which is a pretty clear indication of a power issue. Power issues are our favorite kind, as they're basically the only kind it's really practical to repair, particularly without a BGA machine, and furthermore, they're the sort of issue you're most likely to cause through overclocking, which is way more [H]ard than if your graphics card just lost it's will to live.

Our first step is to test resistance on the 12V input rails. We do this first so that if there's a short to ground on any of them, which is a common mode of failure, we know not to power the card up until we've cleared the short.

The near 8 pin connector. I mention in the video that this is probably OK, but hindsight being 20/20, I should have recognized this as faulty. Still, higher is better than lower here, so this is actually not the end of the world.

The far 8 pin connector. Looks healthy.

The PCI-E input pin. Also looks healthy.

Next, we'll plug the card in and apply power, so we can see which DC rails are actually running. We can't probe all of them with the backplate on there, but doing this with the heatsink installed is the best way to avoid the risk of smoking the GPU die. As described by the previous owner, we get nothing on the screen.

5V rail looks healthy.

3.3V also looks healthy

VCore, though, not so much. This should be in the 700 to 1200mV range. 230 is way low.

That's everything we can really test with the backplate in the way, so it's time to remove it.

With the card torn down, we have much better access to do our normal resistance tests. Here's VCore. Looks healthy. Normal should be something like 1.5-4 ohms.

The memory rail looks healthy. 90ish to 150 is what we expect here.

Memory controller also looks healthy. On a 290 or 290X, you'd expect a bit lower than this, but it's in the realm of normal.

The card's obviously dead, though, so something is clearly still wrong. Let's look at that near 12V input again. A nice thing about this card that I wish more graphics card makers would do is that they've included fuses on each of the input power rails. This means that we're much less likely to burn a hole in the board itself like the 980 Ti did if we have a short somewhere. In the case of that 980 Ti, I suspect the initial failure was actually a power stage, which shorted the input power to ground, and because there was nothing to turn it off, it melted the traces feeding that failed power stage together, destroying the board. A fuse on the 12V input power probably would have saved it.

We know from past experience that the 12V input on these GCN cards should typically be 5K-10K, so that near power connector that read in the millions is suspect. Let's check those fuses.

We've got continuity between the connector and the fuse...

But no continuity across the fuse. So, we know that this fuse is blown.

The other fuses appear to be OK. (Far 12V and PCI-E input, respectively)

It turns out that the near 8-pin is connected to the top 3 VCore phases, plus the memory power.

The far 8 pin is connected to the lower 3 phases.

If we check resistance to ground on the 12V input for those first three phases, we've got a dead short to ground, so now we need to figure out where it is...

Anyone care to guess as to how we find the short?


Feb 11, 2001
Alright, video here:

This card's VCore VRM is made up of our old friend, the IR3567B and a series of six IR3553 DrMOS power stages. A DrMOS power stage is a fancy integrated circuit that contains the driver logic and both MOSFETs in a single package. They're attractive to board designers for various reasons, but one of the most important is that they're way more compact. Here's a 290X for comparison (top). See how much less space is taken up by each phase on the 390 (bottom) versus to the 290X? It's enough that they were able to fit a whole extra phase on there.


I always did like the idea of making the MOSFET's casing metal, and using it as a heatsink, though, which is what's going on with the metal-cased MOSFETs on the 290X. That's a pretty cool feature.

Anyway, The IR3553 does not have a particularly good reputation, as it maxes out at about 40 amps of current output, which is not really all that much on a card this thirsty. Youtube is awash with folks who found that an IR3553 failed on their card, and in many cases they were able to repair the damage by replacing one or more of their 3553s. I was all set to remove the top 3 IR3553s, when it occurred to me to give the board one last look over. I started looking at all of the components that could possibly cause a short to ground, when something about this 0805 capacitor you see marked here just... didn't sit right with me. I tried and tried to get a clear photo of it, but this was the best one I got. I should probably invest in a macro lens if I'm going to keep doing this...


The visual difference was very subtle, and I don't think it would have been clear without a microscope, but as I dragged a fingernail across it, it would catch on something, as if the capacitor was cracked. In contrast, all of the other caps in that row are smooth. A fingernail glides right across them.

So, I decided to try removing that capacitor first.
Flux on...

I tried my soldering iron first, but the tip I have on it is too small to heat both pads at the same time.

The hot air wand made easy work of it, though.

And it's off!

With the suspect capacitor removed, I was able to test the circuit's resistance again, and... Yes! A few thousands is what we want to see here. You'll remember we saw 10K on the far 8-pin connector. I'm probing the pads for the removed cap, but these pads are connected to the near 8 pin's fuses and ground, respectively.

Just to be sure, I tested the removed capacitor. Sure enough, it's in short.

I also removed its buddy, so I could measure it for the replacement. It's 10uF, for those wondering. I know that the other one is also 10uF because the datasheet for the IR3553 specs two 10uF caps in this location.

I then ordered fresh fuses and caps from Digi-Key, and called it a day. We'll have to reconvene when they arrive and I can install them. I should note that this short is not necessarily the only issue with this card, but it's the only one that's currently obviousl


Jan 20, 2019
great writeup as always! I enjoy reading about your fixit adventures and appreciate the skill and tenacity that goes into them. wishing you success on this latest repair!


Feb 11, 2001
Video version here:

Moving right along, at length, our replacement parts arrived, consisting of cut tape reels of 10uF 0805 package MLC capacitors and 10A fuses.

Here's the dead cap removed, with a quarter, for scale. They're very small, obviously.

Our first step today is to replace the fuses - the gold colored ones shown here. It's not clear to me why they use different fuses for each input, other than that the code on the other input's fuses indicates they're a lower amperage. So, the current draw from each 8 pin connector isn't perfectly balanced.

I used hot air to remove the old fuses. When they're attached at both ends, you pretty much have to, unless you have a set of hot tweezers.

I decided to try using my soldering iron first, as it's easier to avoid damaging something else than when using hot air. I'm almost ashamed to post a photo of this, but they're on there, and yes, they're crooked, and also yes, I tagged that connector with the iron. In my defense, the photos make this area look much bigger than it is.

With those on there, it's time to test continuity to the Vin pin on our DrMOSes. This is what we want to see - you may remember that previously, we had about 50M here.

I also checked to make sure I didn't cook the other two fuses, as the one nearest the replaced fuses looks a bit discolored, and it's not flux residue. They're still good, apparently.

For the SMD caps on the back of the card, hot air is the only way to go, especially in this case where there's so much room to work.
Pads cleaned and tinned...

Flux on...

New caps on...

And done!

The solder on these looks better. Note the shinier leaded solder, versus the lead-free solder used for the original parts.

Once again, we need to check for proper resistance. Here, we're testing to make sure that we haven't created a short by bridging the tiny solder pads for those capacitors with a glob of solder. This looks good.

It's now time to plug the card in and test. Cross your fingers, and...

Yes! We have a picture!

Now that we know the card at least kinda works, let's put it back together. First step was to clean off the flux residue. This took forever; I really need an ultrasonic.

But I had to take a break to feed Texel...

And then I cut new thermal pads. I couldn't find my ruler, so I used this dead 980 Ti. :D As with most cards, it seems, the best replacement thermal pad stuff is the 0.5mm size. The stock pads are a hair thicker, but they're also much softer.

Finally, with the card assembled, I booted into Windows and installed the drivers. As you can see here, it's working fine. I did some benchmarking, and as far as I can tell, the card performs exactly as it should. I get a hair under 9000 in FireStrike, which seems about right for this card and an FX-8350.



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Apr 27, 2021
Hello and good job.
Can you help me?
i have problème with my r9 390 sapphire nitro.
Thank you
I have Black screen and no boot.
I have tested all V and i have no V to vmem.
And two capacitor.
Thank you
With other test i have connect to power and i have 2 mosfet 4c10n with 12v and 2 other with 0v and capacitor 0v .
See picture.
Thank you


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Feb 26, 2005
I just bought one that has "issues". Going to see how bad it is. So far my luck has been pretty good and it's usually stuff like just a repaste job being needed. It seems like the Zotac rtx 3080s have a tendency to melt their thermal pads though.


Feb 11, 2001
For some reason I thought you got a lot of dead GPUs from forum members.
I don't do it as a business, but on a few occasions I've had folks send me dead cards to see if I could get them working. Generally, the agreement is that I'll take as long as I need, make a thread or some Youtube videos about it, and not charge anything for labor. I've never had anyone send me a card as valuable as a 3080, though. It's usually old junk like 980 Tis or this 390 where the next step is the E-waste bin.

With something like a 3080, I would think it would be easier to just RMA it, if all you want is a working card. That said, if you run out of options, you're welcome to reach out via PM and we can discuss.


Feb 11, 2001
Oh, I thought you did it as a business.
Nope. It's just a hobby.

Honestly, even under the current conditions, I don't think it's possible to do profitably, if the profit is supposed to come from the repair itself. It takes so long to guess your way through the diagnosis that I'd have to charge like $1000 per card to make a living doing this.

Still, if you really do end up with a dead card you can't RMA, repairing it may be an option we could look at.