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Question High Run & Idle temps? Ryzen 9 3900x

Airplaneotaku

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Aug 8, 2016
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Have a Ryzen 9 3900x Full Stock- no overclocks- running in a full custom loop, 2x 1080tis in the loop after it.
Running F@H overnight gave me consistent 39C on GPU 0, but CPU was throttling to 94.9 C.
Idle is about 53C.
These are numbers from HWInfo x 64. This is a problem since I was HOPING for the full 4.6 boost at least.

I used the included Kryonaut paste and connected the water in the proper direction. Two pumps (it's a big loop) going the right direction.

2x360mm radiators which should be more than plenty, both with double sided fans. CPU package power at max was 134.175w, CPU waterblock is Aquacomputer Cuplex Kyros.
 

Airplaneotaku

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Right, so you're in agreement that it's abnormal?

I added automotive A/C UV dye to the loop for leak testing, I see some strands in the res, but I don't think it could have this much impact. I'll connect the pumps in reverse to check. I'd like to avoid breaking the loop as I would need to retest, and I'm completely certain the paste has good contact.
 
I think it's abnormal....and with water cooling I think it's one of four things.
-The heat exchanger isn't snug on the CPU.
-The coolant is too warm when it gets to the CPU.
-The coolant isn't moving fast enough.
-The fans aren't moving fast enough.
 

Airplaneotaku

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I have a flow monitor at the lowest pressure point of the loop, about how many turns should I be expecting? I have two fans immediately after each other because this is a big, external loop, but they are connected via 3pin fan only and on the same Molex adapter/splitter.

Each rad is pointed out my window and has a fan on both ends, mostly eBay $5/dozen fans but two or three high pressure ones on Push side.

The CPU is first thing in the loop, I made sure of that, and the GPUs aren't nearly as warm as it is, so it can't be water temp.

I plan to hook it up in reverse and try and push backward through the CPU block to see if any particles/clumps come out.
 
by a pair of GPUs 'in the loop after it', I will assume you mean all three are cooled by the one radiator, but, the GPUs come after the CPU? That matters little, as their combined heat likely serves to raise the coolant temp over time to a level that the coolant can only be cooled so much in it's brief trip thru the radiator, likely rendering the CPU cooling capacity to that it is no longer even as effective as a premium air cooler....
 

Airplaneotaku

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Read the OP.
2x360mm radiators. GPUs are behind the cpu. I could potentially add a third but it wouldn't really help as it's bottlenecked by waterblock.
 

intramorph

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Feb 26, 2014
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Dude... I have the same temps. I only overclocked to 4.0GHZ at 1.2V and my temps at idle are 54C
That's on HW monitor. Also have a water cooler AIO though not a loop. AMD 3900X runs very hot for my taste.
Also If I OC to 4.3GHZ I get over temp error immediately. I can't even go to 4.2GHZ because of thermals.
 
Aug 30, 2019
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I've got something really similar happening.

I just built a new liquid cooling loop. At idle, temps are 32C. When I put load on it, temps instantly spike up.
  • Prime95 Smallest FFTs (high heat): 82C
  • Prime95 Small FFTs (max heat): 87C
Temps jump up instantly, then when I stop the test they instantly drop back to idle ~32C. I hadn't expected them to spike that high.

Things I've tried thus far:
  • Reseat the CPU block. 4 times. With different thermal pastes (both from Thermal Grizzly). And different application methods.
  • Flipped the block upside-down. It's mounted symmetrically, so I figured it's worth trying.
Other things of note:
  • 2080 TI is liquid cooled. Idles at 27C. During load it slowly rises to ~48C.
  • Chipset is liquid cooled. Idles at 30C.
  • Case is currently open during testing, so no restriction on airflow (at radiator or anywhere else).
  • Fans & Pumps are running at maximum during all the above tests.
  • Liquid temp is sitting between 26-28C. It really doesn't move much.
  • Flowmeter is moving well. Pretty sure there's no kink or cutoff in flow.
  • Temps measured in Ryzen Master.
  • The water is definitely flowing in the right direction through the CPU block.
  • I'm using the most recent BIOS (v1.80).

Someone replied to my thread on LinusTechTips forum and said this is "normal" for 3900x.

https://linustechtips.com/main/topic/1099753-help-high-temps-on-new-liquid-cooling-loop/
 

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