Ram issue after oc

I have 4x8 gskill 4000mhz running at xmp. Then I turned the bclk to 101 and the ram runs at 4040mhz. I test aida64 and realbench and they both stablize but somehow when I turn on the pc. It does not post instantly. It turns kn and off a few times then memory ok appear on the screen and I have to log in bios to set the setting back. Is it because ram not stable?

So little information to work with.
Based on what little you have said, Its possible your CPU doesnt like the fsb overclock.

I thought its the ram because it says memory ok! after post.

Run memtest86 and see what you get.

try upping the ram voltage 10%