Poor man's guide to servicing a used RTX 3090 for local LLM inference
Posted by canred@reddit | LocalLLaMA | View on Reddit | 19 comments
Wrote up the whole process with disassembly photos and HWiNFO before/after data. Hope it saves someone some headaches.
ttkciar@reddit
This keeps getting reported for self-promotion, but I'm leaving it up because OP has an account history of interacting conversationally with the community (and not with bot-slop).
The rules against self-promotion are partly to prevent outsiders from simply dropping a link on the sub and neglecting meaningful interaction, but I'm not seeing that with canred, so am happy to leave this post up.
canred@reddit (OP)
I'm happy to hear this, thank you. Having said that, I add a few words of explanation:
- the "self promotion" bit really puzzled me. The reason I've sent this to reddit was obviously to make it more visible (the repo lives in github) but I didn't have any other expectations. I'm not looking for a job and I'm not trying to sell you anything.
- I have long history of creating stuff to the drawer, most of my projects has never seen the daylight. While I understand that people get oversensitive on the topic of abusing ai tools, for me personally this is something that finally allowed me to publish stuff that otherwise would be lost in the depths of the phone/obsidian/forgotten folder on disk. I used ai assistant to draft doc structure, to build the repo structure, on different projects I'm actively using it to brainstorm and plan the apps, commit the code - building and pushing container images - all the boring, supporting stuff that I'd normally spend way to much time on. Having said that - in-your-face, autogenerated pic on the top of the writeup was probably to much. I still think its funny but I'll move/remove it because it clearly bites me in the arse here.
- and finally - the usefulness of the writeup. I totally understand that service tech who eats thermopads on breakfast and spread thremal paste on his toast will smile seeing this. This is not my audience. The original audience for this writeup was: myself and the guy who sold me the card. Later on I decided to structurize it a little bit and publish to github. I probably will expand it some time soon, when I decide to replace thermopads. If I was dealing with damaged card, I could potentially add some basic electronics checks like checking basic voltages or tests for short circuit in few places I know they can happen but this was not the case here and I dont feel competent enough to create full repair tutorials for modern cards - I can identify and replace broken capacitor but this is an extent of my knowledge - I wont teach anybody how to reball the memory chips - this was just the basic service tutorial and it is not pretending to be anything else.
NinjaOk2970@reddit
Just say "I changed thermal paste". This is worthless ai slop.
canred@reddit (OP)
fair point on brevity, judging by the reaction it's probably not for you. If you change thermal paste daily for a living it won't have value for you — I do this every 5 years and every time have to do digging, that's why I made a writeup this time.
Velocita84@reddit
"fair point" is the new "you're absolutely right"
reto-wyss@reddit
As someone who does it once every five years, that makes you one of the most qualified people to provide guidance on the matter.
Now excuse me, I'm off to write my guide on how to do amateur lobotomies like a pro. I haven't done any yet, but I could see myself getting into it within the next five years.
legos_on_the_brain@reddit
I was hoping it would be a guide to diagnose the non-functioning ebay 3090's
ArtfulGenie69@reddit
Everyone with their paste brands lol. It really doesn't matter much, I'm still just using arctic silver that came with some other heatsink installed on my cpu. What matters is good contact and making it so the backplate isn't fucking you in the ass. Either remove the back plate completely or add some of those thick blue heat transfer pads and you'll have a much better time. Make sure you refresh the pads on the front too on the ram but the main heat trap is on those stupid fucking back plates. The other thing you'll run into during disassembly is the fan connector gets super hard and old, you may crack the plastic thing on the board just unplugging it, try not to but don't freak out it's still usable. Oh and new fans are under 20$ for a full set on eBay. Good luck!
McSendo@reddit
You should look into the honeywell PTM 7950 (I forgot what it's called). Every thermal paste I used suffered fro the pump out effect, and I would've to replace it every half a year or so. Not with the PTM 7950.
canred@reddit (OP)
You're another person telling me I may have issues with kryonaut, I'll definitely keep an eye on temps over time, thanks!
Eyelbee@reddit
Main problem is vram temps most of the time.
canred@reddit (OP)
I may end up replacing thermopads eventually. I did not do that because my limited experience tells me that original thermopads are often much better quality than what I have access to. Another thing is I don't have service manual for this card and eyeballing correct thermopad thickness can be tricky.
brickout@reddit
What's going on with the memory junction temp?
canred@reddit (OP)
Before repaste, card was thermally limited (look at performance limiter section) - temperatures were to high and card was spinning the fans at 100% and limiting clock frequency to not overveat components. When card was repasted, die could be cooled more effectively, as a result, card was no longer throttling and can now work at full clocks, full power and despite this, fans do not have to work at full speed. Mem junction temp increased because memory finally started to work at full capacity and heat up more, as it should.
brickout@reddit
Ah, makes sense. Thank you.
seamonn@reddit
Kryonaut is a terrible paste for longevity. It's mean for overclocking. It tends to tank in performance a couple weeks into the repaste. Duronaut is what you should be using.
patricious@reddit
Even better, PTM 7950.
canred@reddit (OP)
I used thermal kryonaut before on my ryzens and radeon, used it because I know it but thanks for this info, I'll try to remember
lit1337@reddit
thanks, been looking at some defuct cards to save some money, definitely will be saving this.