Keeping core temperature down on Ryzen 9

bur · 2023-01-06, 13:30

Because it took me quite a while to figure it out, maybe it can be of use to someone :)

On a 12-core Ryzen 9 3900x I had 4 instances of LLR2 with 3 threads each running and core temperatures went to 95 °C and beyond causing the system to throttle every few seconds.

By setting the PPT value one can limit the power drawn by the CPU. This makes it possible to achieve very stable temperatures with a small hit on performance. The irusanov fork of zenstates-linux allows setting PPT on the fly, same as RyzenMaster does under Windows.

Code:

git clone https://github.com/irusanov/ZenStates
sudo ./zenstates-linux --no-gui --ppt 130

Play around with PPT until you find a value that suits your needs in regards to temperature and performance. I brought temperatures down to a constant 80 °C with about 5% loss of speed for LLR2. What could also be done is to look into curve optimization to get some of the lost performance back, but I couldn't find a CLI tool for that yet.

A note regarding the L3 cache. Since 3 cores share 16 MB of L3 cache among them, it's obviously good to keep multithreaded processes confined to a group of 3 cores (CCX) - the governors aren't smart enough for that, I think. But I couldn't find the layout anywhere, i.e. which processor belongs to which CCX under linux. With a lot of trial and error I found that:

Code:

CCX   Processors
0     3, 4, 5
1     6, 7, 8
2     9, 10, 11
3     12, 13, 14

I was used to 0-12 being on separate physical cores, but not so. What made it worse was that /proc/cpuinfo had different mappings of processor to core-ID altogether with IDs 3, 7, 11 not being used at all. Maybe it's specific to this motherboard and/or Linux version though or I just didn't understand the theory behind it.

a1call · 2023-01-06, 14:24

With my 16 Cote Ryzen 9 system, what works for reducing the core temps, is to use more threads around 30.
For what ever reason this cools down the system, reduces performance per thread and keeps the overall progress virtually the same as running at 16 threads.
ETA, this keeps the core temps around 65° C (with liquid cooling).

pepi37 · 2023-01-21, 23:58

I use different method to cool down my Ryzen 9 3900X : I lower cpu voltage under MB BIOS, and dont OC. So even on hottest day with air cooling ( 2 fans on pushpool mode) CPU doesnot go above 75°C. I download script somewhere and put it in crontab so if CPU die temp goes above 80°C ( if day is extreme hot) then shutdown immediately. I say to myself: better to do job few days more then have to buy new MB or CPU. Now it works for 2,5 years without single problem.

2023-01-06, 13:30	#1
bur Aug 2020 796581e-4;32539e-3 2D0₁₆ Posts	Keeping core temperature down on Ryzen 9 Because it took me quite a while to figure it out, maybe it can be of use to someone :) On a 12-core Ryzen 9 3900x I had 4 instances of LLR2 with 3 threads each running and core temperatures went to 95 °C and beyond causing the system to throttle every few seconds. By setting the PPT value one can limit the power drawn by the CPU. This makes it possible to achieve very stable temperatures with a small hit on performance. The irusanov fork of zenstates-linux allows setting PPT on the fly, same as RyzenMaster does under Windows. Code: git clone https://github.com/irusanov/ZenStates sudo ./zenstates-linux --no-gui --ppt 130 Play around with PPT until you find a value that suits your needs in regards to temperature and performance. I brought temperatures down to a constant 80 °C with about 5% loss of speed for LLR2. What could also be done is to look into curve optimization to get some of the lost performance back, but I couldn't find a CLI tool for that yet. A note regarding the L3 cache. Since 3 cores share 16 MB of L3 cache among them, it's obviously good to keep multithreaded processes confined to a group of 3 cores (CCX) - the governors aren't smart enough for that, I think. But I couldn't find the layout anywhere, i.e. which processor belongs to which CCX under linux. With a lot of trial and error I found that: Code: CCX Processors 0 3, 4, 5 1 6, 7, 8 2 9, 10, 11 3 12, 13, 14 I was used to 0-12 being on separate physical cores, but not so. What made it worse was that /proc/cpuinfo had different mappings of processor to core-ID altogether with IDs 3, 7, 11 not being used at all. Maybe it's specific to this motherboard and/or Linux version though or I just didn't understand the theory behind it.

2023-01-06, 14:24	#2
a1call "Rashid Naimi" Oct 2015 Remote to Here/There 2×7×13² Posts	With my 16 Cote Ryzen 9 system, what works for reducing the core temps, is to use more threads around 30. For what ever reason this cools down the system, reduces performance per thread and keeps the overall progress virtually the same as running at 16 threads. ETA, this keeps the core temps around 65° C (with liquid cooling). Last fiddled with by a1call on 2023-01-06 at 14:28

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2023-01-21, 23:58	#3
pepi37 Dec 2011 After milion nines:) 2×3²×7×13 Posts	I use different method to cool down my Ryzen 9 3900X : I lower cpu voltage under MB BIOS, and dont OC. So even on hottest day with air cooling ( 2 fans on pushpool mode) CPU doesnot go above 75°C. I download script somewhere and put it in crontab so if CPU die temp goes above 80°C ( if day is extreme hot) then shutdown immediately. I say to myself: better to do job few days more then have to buy new MB or CPU. Now it works for 2,5 years without single problem.