It should not revert, unless you make a bios.
The fix:
Go into the bios and load setup defaults and re-boot (in you have a RAID, change that setting only). Go into windows and check that it is 16x. Re-boot, go into the bios and load your custom settings. load windows and re-check that it is 16 times. If not, do it again.
I have had that problem many times. But, after I loaded that last bios, I have not went in there and have not had the problem since. I am very sure it happens after you go into the bios.
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