Does BIOS control the memory speed, or does MEMTEST86 force the OEM speeds?

[Dr Jeff]

I am manually setting my memory speeds in BIOS instead of allowing it to auto configure them. In this case I have 1600Mhz RAM that I am slowing to 1333Mhz.

Since there is no real time clock for the memory, I am not 100% sure that MEMTEST86 is running at 1333 vs the OEM set value of 1600.

One would assume that the BIOS is still going to control the speed, and that the memory will be operating at 1333Mhz, but I would like to be sure.

Could anyone shed any light on this?

[David (PassMark)]

MemTest86 reports on the SPD data in the RAM (which what the RAM vendors claims the RAM can support).
It doesn't report the speed selected in BIOS.
It doesn't change the speed selected in BIOS.

[Dr Jeff]

Perfect. Thank you!