[SOLVED] Ryzen 9 3900XT temp question

Oct 29, 2019
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I’m having a weird temperature situation with my Ryzen 9 3900XT. The motherboard is Gigabyte B550I AORUS PRO AX (latest BIOS). The CPU cooler is Kraken X53 (240mm AIO with Noctua fans). The case has ample ventilation.

I have all sorts of software installed (Visual Studio, SQL Server, Microsoft Office, various tools), but at idle nothing’s running in the background (at least to my knowledge). So at idle (task manager shows 1% CPU utilization) the CPU temperature cycles constantly: from around 40C it jumps to 60C or so, then in a few seconds drops back to 40C, rinse and repeat. The cycle takes about 5 seconds.

The pump is at 100%, the fans are on a very aggressive curve, and the liquid temp is 35C.

I’m disconcerted by this constant 40C-60C-40C cycle.

At full load (CPU-Z “Stress CPU”) CPU temp reaches 80C after a minute and liquid goes up to 39C. After a little while CPU temp can reach 85C.

I’ve used a Celsius+ S24 (mounted twice, once with too much thermal paste, once with the right amount) and the aforementioned Kraken X53, same story with both of those coolers.

So I’m thinking, either something’s seriously wrong here, or a 240mm AIO is not enough for the Ryzen 9 3900XT. What do you guys think?
 
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I’m disconcerted by this constant 40C-60C-40C cycle.
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That temp spiking is normal with Ryzen processors. It happens as the processor boosts a core from idle to max clocks for processing a transient load quickly then goes back into an advanced sleep state (C6). It can make that transition up to 100 times a second. There are literally dozens of temp sensors scattered all over the processor dies (two CCD's in a 3900) and it reports out only the hottest one at any given moment.

Each temp spike that results is really very low energy, exactly like a match lighting in a room where there is a temp sensor right on the match so you read a high temperature but the room temperature is unaffected. Just as it's impossible for your AC system to cool off the match, it's impossible to expect your AIO to cool off the temp spike.

What you need to check is an 'averaging' temperature readout which will better reflect the processor thermal state. That's going to be Ryzenmaster but HWInfo also has a "TDie(average)" reading that works similar.

Also, the regular nature of the spikes is just reflecting one (or several) background processes that Windows kicks off on fairly regular intervals. There are over 80 background processes in my Windows, most don't do anything but some kick off every so often for various arcane reasons.

If you have an aggressive fan curve then they may be pulsing as the temperature spikes since, unfortunately, BIOS CPU readings don't average. What I do is relax the curve so it ignores the spike, only starting to raise fan speeds from just sub-audible levels when the core temp gets to 65C or so.
 
Last edited:
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I’m disconcerted by this constant 40C-60C-40C cycle.
...
That temp spiking is normal with Ryzen processors. It happens as the processor boosts a core from idle to max clocks for processing a transient load quickly then goes back into an advanced sleep state (C6). It can make that transition up to 100 times a second. There are literally dozens of temp sensors scattered all over the processor dies (two CCD's in a 3900) and it reports out only the hottest one at any given moment.

Each temp spike that results is really very low energy, exactly like a match lighting in a room where there is a temp sensor right on the match so you read a high temperature but the room temperature is unaffected. Just as it's impossible for your AC system to cool off the match, it's impossible to expect your AIO to cool off the temp spike.

What you need to check is an 'averaging' temperature readout which will better reflect the processor thermal state. That's going to be Ryzenmaster but HWInfo also has a "TDie(average)" reading that works similar.

Also, the regular nature of the spikes is just reflecting one (or several) background processes that Windows kicks off on fairly regular intervals. There are over 80 background processes in my Windows, most don't do anything but some kick off every so often for various arcane reasons.

If you have an aggressive fan curve then they may be pulsing as the temperature spikes since, unfortunately, BIOS CPU readings don't average. What I do is relax the curve so it ignores the spike, only starting to raise fan speeds from just sub-audible levels when the core temp gets to 65C or so.
 
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Oct 29, 2019
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Thank you drea.drechsler, that was very informative.

Unfortunately I can't use Ryzen Master because I'm using virtual machines. But I've just installed HWiNFO64 and indeed the average temp is quite a bit lower that the constantly pulsating temperature I was reading in NZXT CAM and in CPUID HWMonitor. Die (Average) is showing 46C.

I'm gonna try playing with the fan curves in BIOS, thank you for that tip. :)

Now, what about the 85C under load? Should I be worried about that or is it withing specs? I believe I've read somewhere that 95C is the max.
 
Thank you drea.drechsler, that was very informative.

Unfortunately I can't use Ryzen Master because I'm using virtual machines. But I've just installed HWiNFO64 and indeed the average temp is quite a bit lower that the constantly pulsating temperature I was reading in NZXT CAM and in CPUID HWMonitor. Die (Average) is showing 46C.

I'm gonna try playing with the fan curves in BIOS, thank you for that tip. :)

Now, what about the 85C under load? Should I be worried about that or is it withing specs? I believe I've read somewhere that 95C is the max.
95C is Tjmax, that's true. The processor should start throttling (as opposed to just pulling boost clocks) to protect itself at that temp. Fused-in shut down protection doesn't kick in until 115C or so, but we don't want it ever to get to 95 for extended periods even in testing.

85C isn't abnormal under REALLY heavy, like AVX, workloads. But it's not desireable bacause the processor starts pulling boost clocks heavier above about 80C. But a stress test isn't 'normal' by any means: how does it do in your regular workloads?

I run my system (a 3700X under 240mm AIO) with PBO and I've set a platform thermal limit at 85C to throttles the CPU at that level. It works quite well, never throttling heavily but keeping from going above 85 at the same time. It only ever gets above 75-76C in Prime95 testing though!
 
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Oct 29, 2019
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how does it do in your regular workloads
I just built this machine so I haven't had a chance to put it under heavy workload yet. But using Agent Ransack to search for a string inside files on the SSD (which is something I would use in real life once in a while), it uses all the cores and I'm seeing 84C.

I guess a 280mm AIO would have been better, but I'll live with the 240 I have... for now.

Thank you again drea.drechsler for explaining all this to me.
 
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I guess a 280mm AIO would have been better, but I'll live with the 240 I have... for now.
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Actually, I'm not sure it could help unless they also have way more efficient water blocks. The radiator size (from 240 to 280 or 360) really only helps by increasing liquid volume and increasing surface area to improve heat transfer from the liquid to air. That helps increase time before the liquid thermally saturates; it usually takes a couple hours but when, or if, it does temperature will start to bloom way out of control. But with the same water block (which includes the pump in an AIO) as a 240mm even a 360mm won't transfer heat from the CPU to the liquid any faster.

The rate at which it can transfer heat from the CPU to the liquid can only be improved if the water block is also improved...larger heat plate, more/deeper finning inside and higher capacity pump usually. That's the domain of custom closed loop systems for the most part.
 
Oct 29, 2019
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That's a good point. And I'm definitely not going the custom loop route. The reason I was thinking a bigger radiator and fans might help is because when the CPU is under heavy load, the liquid temperature increases by a few degrees.

I'm looking at it right now, after a few minutes under high load, the liquid temp went from 38 to 41C. It seems to have stabilized there so it doesn't look like it's gonna go out of control anytime soon. But I'm thinking, a 280mm AIO might be able to keep the liquid just a bit cooler, which would help with the CPU temp.

It may or may not be worth it... In any case it would have to wait for my next paycheck. In the meantime, I've tweaked the fan curve as you suggested and it made a big difference, it's much quieter now.
 
Oct 16, 2020
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I’m having a weird temperature situation with my Ryzen 9 3900XT. The motherboard is Gigabyte B550I AORUS PRO AX (latest BIOS). The CPU cooler is Kraken X53 (240mm AIO with Noctua fans). The case has ample ventilation.

I have all sorts of software installed (Visual Studio, SQL Server, Microsoft Office, various tools), but at idle nothing’s running in the background (at least to my knowledge). So at idle (task manager shows 1% CPU utilization) the CPU temperature cycles constantly: from around 40C it jumps to 60C or so, then in a few seconds drops back to 40C, rinse and repeat. The cycle takes about 5 seconds.

The pump is at 100%, the fans are on a very aggressive curve, and the liquid temp is 35C.

I’m disconcerted by this constant 40C-60C-40C cycle.

At full load (CPU-Z “Stress CPU”) CPU temp reaches 80C after a minute and liquid goes up to 39C. After a little while CPU temp can reach 85C.

I’ve used a Celsius+ S24 (mounted twice, once with too much thermal paste, once with the right amount) and the aforementioned Kraken X53, same story with both of those coolers.

So I’m thinking, either something’s seriously wrong here, or a 240mm AIO is not enough for the Ryzen 9 3900XT. What do you guys think?
Hey Leptir,

I had the same problem with my 3900xt even with a 360mm AIO. Later I discovered the Ryzen power plans are CPU KILLERS because they feed your CPU unnecessary high voltage even when its idle, So I decided to change it to windows default balanced power plan. Since then my idle temperatures are like 35C and under. It also solved the problem of constant temperature jump cycles like you are experiencing. I hope this helps. Also make sure you have good air flow for the cabinet.
 
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Oct 29, 2019
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Hi Malik! I had it on "Ryzen High Performance". So I changed it to "Balanced" as you suggested. Temp has dropped a little bit. 🆒 I'm still getting the weird little temperature dance, but it's no big deal. I adjusted the fan curve as drea.drechsler suggested and that made a huge difference. Now with your suggestion, it's idling at 40C with fans running at low rpm. I guess that's good enough. Thank you for that suggestion!
 

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