Quote Originally Posted by johnw View Post
Not all motherboards have the problem with lower 4KB random reads when processor C-states are enabled. But I'm not sure which motherboards are which.

Also, remember that CDM sometimes gives strangely high results for 4KB read on Sandforce SSDs.

What does AS-SSD measure?
I'll say that it's the MB's using the PCH that are mostly affected. (I'll do some tests on the ICH to confirm)

CDM is not using threads and I can't find anything wrong with the code.
ASU and AS SSD uses threads and should be close but it's plain to see that AS SSD uses a different approach when measuring 4K in particular.
(AS SSD takes forever on HDD's and uses multiple files when testing QD, ASU and IOmeter uses a single file for QD testing)

As a result of the different approach they will never compare 100%, they should be relatively close, and they are close most of the time.