Expected Temperatures of a Watercooled 4090FE?

Soldato
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Can't always see signatures
Especially when on mobile devices
So no didn't click it lol

Nice now I see it
Wasn't expecting 4 x 180mm
Some reason I thought would be 120mm or 140mm fans
On the external rad

Can't say I have ever had thermal paste pump out
So can't help with that bit
Good to see someone else with a mora has joined in though
 
Soldato
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Thanks for the help guys, now that I know there's an issue and I'm not going mad I can start to investigate it. Just when I was really starting to use the computer it looks like I need to strip it down.

Possible causes in my order of likelihood:
  1. Blockage in the CPU block (EK Velocity2)
  2. Blockage in the GPU block (Watercool Heatkiller)
  3. Blocked filter mesh in the reservoir (AquaComputer Utilitube)
  4. Thermal paste pump-out on the GPU block
  5. Pump failure and not actually circulating the water
  6. Blockage in the radiator
  7. Poltergeist
Let's hope it's not number 7.
 
Soldato
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Well number 7 is a new one
Not seen that before lol

2 choices
Do it in order of likelihood
Or do it in order of easiest/difficulty I guess

The joys of custom watercooling unfortunately

It'll be quite easy to tell if there's a blockage in either block; disconnect the quick disconnects, drain the water then connect a pressure tester with an open loop. Just like I did when checking for leaks, sort of:

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With the loop being open, if the pressure builds up and doesn't immediately vacate, then I've a problem. Tomorrows job, yay.
 
Soldato
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So last night I fired up a few benchmarks (Cinebench R23 and Furmark) to warm up the system to see how each individual waterblock was performing. It wasn't good.

Then I started playing a game and very quickly the temperatures of the 4090 got way out of control - like 86C hotspot temperature! That's not good at all.

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I suspect it's a flow issue with the water, wherever the impediment may be.

So no gaming for me until I find it.
 
Associate
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Possibly flow issue. Not sure how restrictive your GPU block is.
Adding a 90 degree fitting right at output of the pump would greatly reduce flow, specially if one or both of your waterblocks is restrictive. Had similar issue, even at 100% with a D5, using the Alphacool Edge and some Corsair rads. Around the loop, angled fitting won’t cause as much loss.
GPU overheating not necessarily bad mounting I assume it may not be an issue, as rad getting hot may be because of poor flow.
Easy test, remove the angled fitting at the output of the pump and see how it goes.
 
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It'll be quite easy to tell if there's a blockage in either block; disconnect the quick disconnects, drain the water then connect a pressure tester with an open loop. Just like I did when checking for leaks, sort of:

embed


With the loop being open, if the pressure builds up and doesn't immediately vacate, then I've a problem. Tomorrows job, yay.
Pressure won’t flag the real issue. A loop without leak doesn’t mean there isn’t a blockage or the restriction is too much for the pump.
Not your case, but you could have in and out in wrong side of the blocks on an EK waterblock, for example, where the coolant would simply pass without getting into the block and the pressure won’t flag that. Had issues when using an active backplate, and because I assumed the ports should be as single sided blocks, the coolant was simply crossing from in to out without getting into the block channels.
 
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I had a problem with my 7900xtx, my water temp was fine but my detla between core and hotspot was over 30c, before is was 19c between the 2, took my block off and i had thermal paste spill out, re applied and when tested again i had a delta of 18c, core temp was low 40's and hotspot was around 60c.

Check the micro fins on the gpu, if you notice even a tiny bit of gunk or debris, it can have a drastic affect on cooling, but i would do a repaste, can check the micro fins at the same time too, kill 2 birds with 1 stone.
 
Soldato
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That's the computer all stripped, cleaned and rebuilt. While it warms up I'll post some pictures of what I did and tested.

TLDR - I think it's thermal paste pump out on the GPU.

Stripped the reservoir to clean the filter of the Utilitube which was a little dirty from small bits of the EPDM hose that acts as the umbilicals between the computer and the radiator. This wouldn't cause much of an issue as the mesh is just between the reservoir contents and the pump.

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Tested the flow of the pump, this is at 100% and perfectly fine.

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The micro fins of the EK Velocity 2 CPU block look clear except for what looks to be a very small hair.

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The micro fins of the Watercool Heatkiller for the GPU look fine also, a tiny bit of crud but noting I'd think would cause a problem. The gunk around where the o-ring would sit has what I presume silicone to protect the o-ring.

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Here's a close up of the 4090's die just after removing the waterblock. Does this look like thermal paste "pump out" to any of you?

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An image of the waterblock after removing the 4090.

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It certainly looks like thermal paste pump out from the few images I've found from searching. This was a brand new tube of Artic MX-6 too.

The kicker is it's the same stuff I've just used on the reassembly :cry:.

Anyway, gave both block's contact plates a nice ultrasonic bath in some isopropanol alcohol...

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Checked the fins were clean using my smallest feeler gauge

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Pressure tested both waterblocks before refitting them. Better than factory! :D

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Final pressure test before adding water.

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How things are at present, with just an idle workload. I'll start some GPU and CPU workloads up now to bed things in.

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So, thermal paste pump out on the GPU we think?
 
Soldato
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it looks like the gpu paste has gone off, looks super watery which isnt right, and super thin layer too, either pump out or gone off looks to be the issue.

also getting rid of the debris in both blocks will help flow and cooling too :)
 
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This will happen again. Normal thermal pastes are just not good for 4090 die. It will rise back eventually. Also that hotspot/core delta was horrendous.
You have 3 options:
-liquid metal(not worth it imho)
-Thermalright TFX(the most viscous thermal paste on the market)
-Honeywell PTM7950 - this is the stuff 4090fe uses originally. Its not pumping out on mine for the last year - I've had issues even with TFX, but significantly less than any other paste(I've tried multiple pastes over the last few years, both on 3090 and 4090, all are s***t after few weeks/months.)
Rule of thumb is that if hotspot/core delta is >10 degrees under load then it indicates a problem with the paste/mount.
 
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This will happen again. Normal thermal pastes are just not good for 4090 die. It will rise back eventually. Also that hotspot/core delta was horrendous.
You have 3 options:
-liquid metal(not worth it imho)
-Thermalright TFX(the most viscous thermal paste on the market)
-Honeywell PTM7950 - this is the stuff 4090fe uses originally. Its not pumping out on mine for the last year - I've had issues even with TFX, but significantly less than any other paste(I've tried multiple pastes over the last few years, both on 3090 and 4090, all are s***t after few weeks/months.)
Rule of thumb is that if hotspot/core delta is >10 degrees under load then it indicates a problem with the paste/mount.
That’s why I stop using thermal Grizzly Kryonaut. Performance was good, but wouldn’t last long.
Using the MX6 now, but both the 4080 and the 7800x3D are relatively “cool”.
Maybe time for those sheets from Thermal Grizzly or similar?
 
Soldato
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Yeah gpu thermal paste looks terrible
Would say that's main issue
Though coolant temp seemed high before too
It may be worth ordering
Some of the Pastes mentioned
Just in case since you're rebuilding it with
Same paste as first time

Never used a reservoir with a filter
Does make me curious if it affects flow
At all

Yeah thermal sheet may be an idea
Think there's a few manufacturers making those now
 
Soldato
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it looks like the gpu paste has gone off, looks super watery which isnt right, and super thin layer too, either pump out or gone off looks to be the issue.

also getting rid of the debris in both blocks will help flow and cooling too :)

In all my time watercooling I've never seen that pattern of paste when removing a block. It was a brand new tube of MX-6 too.

There wasn't that much debris in the blocks to be honest, I expected something drastic!

Good Lord, seems a complete strip down was inevitable!

How are the temps looking afterwards?

Indeed it was, only way to be sure!

Temps are great now but I have a feeling it won't last....

This will happen again. Normal thermal pastes are just not good for 4090 die. It will rise back eventually. Also that hotspot/core delta was horrendous.
You have 3 options:
-liquid metal(not worth it imho)
-Thermalright TFX(the most viscous thermal paste on the market)
-Honeywell PTM7950 - this is the stuff 4090fe uses originally. Its not pumping out on mine for the last year - I've had issues even with TFX, but significantly less than any other paste(I've tried multiple pastes over the last few years, both on 3090 and 4090, all are s***t after few weeks/months.)
Rule of thumb is that if hotspot/core delta is >10 degrees under load then it indicates a problem with the paste/mount.

Thanks for this post, and yes it's inevitable that it will happen again as I used the same MX-6 thermal paste. It's only a matter of time.

I'm going to order some Honeywell PTM7950 that you mention in preparation for the repasting. I've used liquid metal in a previous build and it was a pain, it's not going anywhere near the 4090! :)

That’s why I stop using thermal Grizzly Kryonaut. Performance was good, but wouldn’t last long.
Using the MX6 now, but both the 4080 and the 7800x3D are relatively “cool”.
Maybe time for those sheets from Thermal Grizzly or similar?

Interesting that you're using MX-6 too, it'll be interesting to see how you get on but as you say it may not affect you.
 
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