E3-1575M v5 stuck at 2.8 GHz in Windows 7

[SkyHound0202]

I recently got a mini PC (similar to this one) with E3-1575M v5 with Iris Pro P580 Graphics with the intention of turning it into a Hackintosh Mac mini.

 

When testing in Windows 7, I noticed that the CPU clock speed would stuck at 2.8 GHz for some reason, regardless of the load.

 

 

But in Windows 10, for the same machine with the same BIOS setting, the CPU would boost to 3.9 GHz with ease.

 

 

Could this be caused by the outdated Windows 7 scheduler or something else in the system is preventing it from boosting higher in Windows 7?

 

BIOS setting:

-Power limit disabled

-Energy-efficient boost disabled

-CSM enabled (won't boot into Windows 7 if disabled)

 

Windows setting:

-Performance power plan

 

*Note this processor IS an Engineering Sample (ES), but the testing in Windows 10 suggests this particular processor inside this mini PC outperforms the same processor installed on a laptop due to better cooling and power delivery.