Any reason why a CPU would throttle at 100% utilisation?

[chickadee]

So I noticed a weird quirk, my x5660 at stock will boost up to 3.2ghz and does so regularly.

The weird thing is when i run a benchmark that strained all 12 cores to 100% the speed will jump to 3.2ghz then quickly drop down to 2.8ghz which is the unboosted clock and sit there until the test is stopped then will boost again quickly to 3.2 and then downclock to its idle speed of 1.6ghz.

The temperatures even at 100% never get above 40c and sit at 5c above ambient when idle so the temperatures are fine.

 

[chickadee]

Boost probably isn't designed to run 100% at all cores. It will do 12 cores at 2.8GHz, 8 cores @ 3GHZ and 4 cores @ 3.2GHZ. These are just examples but you get the idea.

OK that makes perfect sense, cheers.