limit cpu usage of cpu client?

[cheechi]

One of my 3 folding PC's is my old gaming system, now set up as an always on game server/PC at my workbench. It is overclocked and summer is here. It's in my unfinished* basement. I'd like to limit the CPU usage to 90% as it does get warm enough that it's hitting the TDP limit for the cpu, but only barely. It runs a Phenom II 965 Black with a 1050 Ti, both folding.

I've searched the main site and this forum, I know that it can be done, but I can't find how to set the limit on the CPU usage. Probably one of those things with too many common words/phrases to pinpoint what I need.

Any help would be appreciated.

Edits:
the basement has a bare concrete floor. There is 1" of rigid foam between block walls and framing, up to the point where the walls are completely underground. It stays cool relative to outdoors, but some days 'cool' and 'cool relative to outdoors' have a great distance between.

PC is running windows 10 x64.

[toTOW]

You can't limit the CPU usage in the way you think ... but you can reduce the number of CPU cores that FAH can use. It's in Slot settings.

[cheechi]

am I thinking of an outdated flag from an older version? I don't remember specifically enough so I am not arguing with you per se, and I do appreciate your help. I could have sworn I have done this in the past with one of my machines.

[bollix47]

You have not included the o/s you're using but here are a couple of additional hints in case you don't want to decrease the # of CPUs:

Windows 10 - under power options - Processor power management - decrease Maximum Percentage

For linux you could setup an rc.local file (if you don't already have one) with something like the following:

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#!/bin/bash
echo 50 | sudo tee /sys/devices/system/cpu/intel_pstate/max_perf_pct

The above should drop CPU maximum GHz by 50% ... the rc.local file should be placed in /etc and should be made executable using the following ... after which you need to reboot so the system reads and executes the rc.local file

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chmod +x rc.local

I've used both methods to bring down CPU temperatures.

[cheechi]

I apologize, due to my assumption that this was a flag feature in the client I assumed it would be OS independent. This is Win 10 and I'm going to try your suggestion, thanks.

[bruce]

There was a flag but it only applied to a single CPU core. If you enable more than CPU:1, the others always ran at 100%. It never worked to give you 90% of (e.g.) 4 cores but you could get 90% of 1 core. Start by configuring CPU:N for small values of N and see if you can get what you want.

If you really want less than 100% of 1 CPU core, the flag might still work but somebody will have to remember what it was or find the documentation.

It never would limit the processing used to support GPUs, or to resources used by non-FAH software.

[MeeLee]

Or, force a lower clock on the CPU in bios. If your bios allows it, you can also undervolt the CPU by .05V, or whatever setting it allows you to undervolt. Performance should be nearly the same, at the same base frequency, but heat generation and power draw should be lower.
Setting it too low could crash the system...

[bruce]

There are several good 3rd party CPU management apps, but my earlier answer was focused on what native FAH can / cannot do. (They're also a lot more complex that just setting one flag.)

[cheechi]

thanks everyone. I appreciate knowing what I remembered from way back when won't be useful now.

Since this PC 'needs' to be on and at the set voltage/clocks for its other role as a game server, the box fan sat next to it will have to do.