Frequency Limit Global for Ryzen 7 7840HS (Zen 4 / Phoenix CPU)

[birdie]

HWiNFO64 says Frequency Limit Global for my Ryzen 7 7840HS CPU is 4500MHz which is far below what AMD says it should be boosting at which is 5.1GHz.

Could this limit come from the BIOS? I'm looking at HWiNFO64 output and I don't see any limits (power, voltage, amperage, etc). being hit.

The CPU never ever goes above 4.5GHz no matter the load. The CPU is pretty much sitting idly.

 

[Martin]

This is a dynamic run-time limit that aggregates several run-time parameters like TDC, EDC, PPT, Thermal, and some other internal ones and decides what's the actual maximum clock allowed.
So it's not a fixed limit defined by BIOS, but constantly evaluated by the CPU/SMU.

 

[birdie]

This is a dynamic run-time limit that aggregates several run-time parameters like TDC, EDC, PPT, Thermal, and some other internal ones and decides what's the actual maximum clock allowed.
So it's not a fixed limit defined by BIOS, but constantly evaluated by the CPU/SMU.

But Martin, as you can see on the screenshot, no parameters' limits are even close to their maximum There's no throttling either. Temperatures are very low.

Is is possible to hard limit the CPU maximum frequency in BIOS/UEFI?

Is it possible to write to some CPU registers to unlock it? Though considering it's a PRO SKU I guess it's all tightly controlled.

 

[Martin]

Yes, I saw that and I'm wondering too. There are also some other internal parameters involved in the decision making which are not visible to the public and I'm not allowed to talk more about that.
Perhaps one of those parameters is enforcing this limit.

 

[birdie]

Yes, I saw that and I'm wondering too. There are also some other internal parameters involved in the decision making which are not visible to the public and I'm not allowed to talk more about that.
Perhaps one of those parameters is enforcing this limit.

I'm reading it as "Limits are enforced/imposed by BIOS". Hopefully they will release an updated BIOS with a lifted restriction. Why did HP do it to me?

Thanks a lot anyways!

BTW, there's something which looks like an error in reporting:

Core Powers Maximum is reported as 109W. I don't think this is possible for this SKU.

And L3 cache running at 287GHz is quite unusual. I don't think silicon can run at such a speed. It's not physically possible

 

[Martin]

Yes, I noticed that too. Must be some issue in the SMU as HWiNFO shows what the SMU reports.

 

[birdie]

Yes, I noticed that too. Must be some issue in the SMU as HWiNFO shows what the SMU reports.

I'm not sure what you're hinting at. A HW failure? AMD Phoenix APU peculiarity?

I've used the laptop for just three days. Please do not frighten me

 

[Martin]

No, a SMU software/firmware failure in reporting of those parameters. Might be fixed with a new BIOS update.