Stability Test Reducing Clock?

[StripeyButt]

So I'm kind of just getting into OCing for the first time and I'm trying my MoBo's auto overclock for this.

 

MoBo: MSI Z270 Gaming M7

CPU: i7-7700K

 

Using the auto OC software, I have my CPU set to 4.6GHz. I can verify this in both the MSI Command Center as well as AIDA64. 

While in the System Stability Test mode, the CPU Clock shows 4610. Great! Looks like it works fine. 

However, as soon as I start the stability test, the clock drops to 4209 and stays there just like it does when it's not OC'd as the base clock is 4.2GHz. I would be under the assumption that since it's OC'd to 4.6GHz, the stability test would ping it at 4600 at least...

 

Is this because I'm just using the trial version? Do I just not understand how this works? Or is something else going on? 

[StripeyButt]

Okay, update:

When I disable FPU from the stability test, my clock now jumps back up to 4600. Can someone explain what FPU is that would make it reduce my clock speed in this stability test?

 

As an addition, I see zero throttling going on in the graphs. 

[Fiery]

On 12/20/2020 at 1:14 AM, StripeyButt said:

Okay, update:

When I disable FPU from the stability test, my clock now jumps back up to 4600. Can someone explain what FPU is that would make it reduce my clock speed in this stability test?

As an addition, I see zero throttling going on in the graphs. 

The FPU subtest puts the most demanding task on the processor which could make it hit TDP, TDC or other power limits or simply overheat, and that will effectively disable automatic overclocking, or prevent any kind of overclocking without potentially damaging the CPU.

In other words, in your particular case what happens is that 4.6GHz is only possible with 90-95% of the tasks (workloads), but the most demanding few of such tasks will only enable a lower CPU clock frequency to be used.