[SOLVED] Constantly Changing 3950x Temperatures when Idle

[barnyard80]

I have a PC with Ryzen 3950x CPU, Asus TUF B550 Gaming motherboard and Noctua U14S CPU cooler in a Fractal Meshify C case.

The OS is Ubuntu 20.04.

When the CPU is idle, the CPU temps are constantly changing between 34C and 58C. This is very annoying as it causes the fan to constantly speed up and down.

I have turned off PBO, but it did not help. What else could I do fix this?

Chart showing the temperature variations and the CPU usage are below:

 

[Zerk2012]

That looks normal for the 3XXX processors nothing you can do about it that I know of.

 

[Phaaze88]

It's normal.
Try setting a fan curve at 70% for both minimum and middle fan settings, and 100% at 80C.
That's assuming your Asus board has the same fan control settings in bios as mine.

 

[CountMike]

No OS keeps true idle all the time, there's always something doing in the background, some times just some maintenance task and some times update, caches etc. That of course changes voltages and with them temperature. Ryzen switches modes very fast so it's quite normal. All modern CPUs do that.

 

[barnyard80]

It's normal.
Try setting a fan curve at 70% for both minimum and middle fan settings, and 100% at 80C.
That's assuming your Asus board has the same fan control settings in bios as mine.

Thanks. That made it sound a lot more consistent. I experiment with setting the fan to only start speeding up from 60C upwards. If the temperature spikes stay under that, then hopefully the fans will stay quiet. But I do not know how high the spikes will go if the fans are set so low.

What are safe operating temperatures for the CPU?

 

[Phaaze88]

What are safe operating temperatures for the CPU?

With how often I see posts about it: these Ryzen 3000 cpus LOVE to boost their frequency until they reach 80C, after which they stop, so I'd say not to exceed 85C.