Weird Issues with semi-working RTX 3080

Andrew_Carr

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Not sure what's wrong with this card so I was wondering if anyone had ideas. It's a Zotac OEM model RTX 3080 that looks like one of these kind of: https://www.techpowerup.com/vgabios/225496/zotac-rtx3080-10240-200901

Anyway, I took a risk and bought it used from someone who said it was broken. I plugged it into a linux HiveOS machine and it was mining fine at 97MH/s and temps seemed fine (about 60C iirc). The next day it wasn't hashing anymore but it's still detected by the OS. If I plug it into a windows computer it will boot and display an output and seems to work fine, but the resolution is limited to 1024x768 and any other resolution is greyed out. When the resolution is increased such as after installing the drivers I get a black screen, but I don't get a "no display" error from my monitor. Also, temp sensors seem to be missing if I check in hwinfo64 or gpuz. When I run it in linux the temps on the core and memory are usually around mid 30C at idle.

I was thinking maybe something was damaged but I've taken it apart and everything seems fine, nothing burnt or anything obvious. Temps also seem fine so I'm not sure what's going on. Usually I figure these things work or they don't, not that they work somewhat like in this situation.

Update: Tried extracting the vbios again using GPUz, but it black screens.

Here's what GPUz and hwinfo64 see:
 

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Andrew_Carr

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Update: Seems to be fixed. I put it in a separate rig with a new PSU, motherboard, everything, removed my power limits on the card, and it's working again now, might've just been a power thing I guess.
 

RazorWind

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Was there any evidence of someone having messed with it prior to coming to you? (Missing warranty sticker?)
 

Andrew_Carr

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Yeah, the previous owner sold it as junk and non-working and said it was recognized in the BIOS but wasn't working. I opened it up to see if it was something simple and it looks like they had already opened it once (sticker missing on screw) and replaced some of the memory thermal pads (the OEM ones were black and plasticky on the backplage, but the ones on the vram etc. were grey and I figure were gelid or thermaltake pads).
 
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How much did you pay? Wonder if it was possible to get a warranty replacement and just claim it was a gift...
 

Andrew_Carr

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I spoke too soon. After an hour it quit on me again. Card is still recognized so I probably have to fix something with something overheating I guess. The trouble is that it's an OEM card with different pad thicknesses than the regular trinity so I roughly compared the pads before replacement but have no reference documents to go off of, and Zotac wouldn't help me with that (or an RMA). I paid $1300 or about half the going rate at the time. My latest buy, a $400 Radeon VII, isn't working either despite looking like it's NIB and untouched so I might have another weekend of tinkering ahead with these cards.
 
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$400 vega 7 is an impressive price for a working card given its hashrate is the same as a 3080...too bad it's not working. You could probably still sell for a profit on eBay for parts or not working.
 

Andrew_Carr

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Yeah, it came from what looked like a big box reseller. The box was still sealed, zero dust/dirt on the card, and when I took it apart just now it looks totally unused (thermal stuff on heatsink is still in mint condition and thermal pads look perfect). No signs of disassembly so I'll have to try to see if I can get it working by maybe using a washer mod or something and lowering temps. The card is recognized by my computer at least sometimes, so it doesn't seem to be totally dead. Probably going to try liquid metal on these to see if it fixes any temp related issues even though temps when the RTX 3080 were mining were in the 70s.
 

Falkentyne

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Yeah, it came from what looked like a big box reseller. The box was still sealed, zero dust/dirt on the card, and when I took it apart just now it looks totally unused (thermal stuff on heatsink is still in mint condition and thermal pads look perfect). No signs of disassembly so I'll have to try to see if I can get it working by maybe using a washer mod or something and lowering temps. The card is recognized by my computer at least sometimes, so it doesn't seem to be totally dead. Probably going to try liquid metal on these to see if it fixes any temp related issues even though temps when the RTX 3080 were mining were in the 70s.

Did you try cleaning the PCIE Slot pins with Deoxit D5? I've seen bad contact cause issues like that.

Also, try disassembling the card fully and completely.
Buy some 99% isopropyl alcohol.
Something like this should work (maybe you can find something similar locally, or a better deal).

https://www.amazon.com/gp/product/B07L6MMV7F/

Douse and submerge the board in it.
See if that fixes it.
I know one person who had a card acting up like this, because when he un-did a conductive paint shunt mod, there was MG 842AR residue flakes bridging something, which became visible floating in the iso bath.
card worked 100% perfectly after that bath.
 

Andrew_Carr

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Hmm.. thanks, just picked some up so I'll give that a shot. So far the D5 has removed a lot of corrosion from the pcie slot. Didn't see anything and I had cleaned it with alcohol previously, but one side seemed to have a decent amount of corrosion.
 

Andrew_Carr

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Did you try cleaning the PCIE Slot pins with Deoxit D5? I've seen bad contact cause issues like that.

Also, try disassembling the card fully and completely.
Buy some 99% isopropyl alcohol.
Something like this should work (maybe you can find something similar locally, or a better deal).

https://www.amazon.com/gp/product/B07L6MMV7F/

Douse and submerge the board in it.
See if that fixes it.
I know one person who had a card acting up like this, because when he un-did a conductive paint shunt mod, there was MG 842AR residue flakes bridging something, which became visible floating in the iso bath.
card worked 100% perfectly after that bath.

Ok, just tried all of that. No luck, still the same situation as before. I'm starting to think it's an issue with the heatsink not contacting the chip well enough. That might explain why the card performs as expected in mining (when it works) and works fine until you load a game. Temps seem ok but maybe they're spiking somewhere on the chip and it's throttling? I have a new batch of thermal pads arriving soon so I'll be able to try all sorts of combinations.
 

RazorWind

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Ok, just tried all of that. No luck, still the same situation as before. I'm starting to think it's an issue with the heatsink not contacting the chip well enough. That might explain why the card performs as expected in mining (when it works) and works fine until you load a game. Temps seem ok but maybe they're spiking somewhere on the chip and it's throttling? I have a new batch of thermal pads arriving soon so I'll be able to try all sorts of combinations.
What does the grease spread on the die look like?
 

Andrew_Carr

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What does the grease spread on the die look like?
I'll take it apart tomorrow and share some pictures. I was putting a lot of thermal paste one earlier but this time I didn't put so much on. I'm down to 0.5mm and 1mm thermal pads on most of the components now so I was thinking the core temps would be ok at least but who knows.
 

Andrew_Carr

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So I'm hoping I fixed it finally. I took it apart again today and it looked like this. I repasted the die and put extra paste on the heatsink just to see if that would help. Then when I removed the metal frame I noticed one of the thermal pads was extending over a vram chip and the edge looked like it had been pushed over the silver bracket surrounding the die, so maybe that was causing poor contact? Anyway, after repasting and putting in a test rig it's mining fine and hasn't had any issues. Will see how long it lasts this time.
 

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Andrew_Carr

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Update: Card worked fine for about 3 hours, temps were all low, then it stopped again. Back to being recognized as a generic card and it seems like the drivers not working. New thermal pads arrive soon so I can try all types of combinations soon I guess.
 

RazorWind

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So I'm hoping I fixed it finally. I took it apart again today and it looked like this. I repasted the die and put extra paste on the heatsink just to see if that would help. Then when I removed the metal frame I noticed one of the thermal pads was extending over a vram chip and the edge looked like it had been pushed over the silver bracket surrounding the die, so maybe that was causing poor contact? Anyway, after repasting and putting in a test rig it's mining fine and hasn't had any issues. Will see how long it lasts this time.

Clean the grease off of the heatsink and die, and check the mating surfaces for flatness with the best straight edge and feeler gauges you can get your hands on. It looks to me like the mating surface of that vapor chamber is really convex (or the die is).

Solution being to lap or replace that heatsink. I'd use it as an excuse to go to water cooling, but maybe that's not practical for mining.

Edit: I don't think you're going to meet with much success just swapping thermal pads.
 

Andrew_Carr

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Clean the grease off of the heatsink and die, and check the mating surfaces for flatness with the best straight edge and feeler gauges you can get your hands on. It looks to me like the mating surface of that vapor chamber is really convex (or the die is).

Solution being to lap or replace that heatsink. I'd use it as an excuse to go to water cooling, but maybe that's not practical for mining.

Edit: I don't think you're going to meet with much success just swapping thermal pads.

Hmm, yeah, hadn't checked that yet. Maybe it's uneven. I don't think watercooling is an option no matter the cost because it's a weird OEM style board, but I can try to smooth out the heatsink.
 

Woot910

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good lord that's a lot of paste. I try to add what is needed so that the surround SMT components are not covered at all...
So I'm hoping I fixed it finally. I took it apart again today and it looked like this. I repasted the die and put extra paste on the heatsink just to see if that would help. Then when I removed the metal frame I noticed one of the thermal pads was extending over a vram chip and the edge looked like it had been pushed over the silver bracket surrounding the die, so maybe that was causing poor contact? Anyway, after repasting and putting in a test rig it's mining fine and hasn't had any issues. Will see how long it lasts this time.
 

RazorWind

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good lord that's a lot of paste. I try to add what is needed so that the surround SMT components are not covered at all...
This appears to have a heat spreader thing that covers the memory ICs, which then requires thermal paste between it and the actual heatsink.
Hmm, yeah, hadn't checked that yet. Maybe it's uneven. I don't think watercooling is an option no matter the cost because it's a weird OEM style board, but I can try to smooth out the heatsink.
Maybe this would fit it?
https://www.ekwb.com/shop/ek-quantum-vector-trinity-rtx-3080-3090-d-rgb-nickel-plexi
 
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