Quote Originally Posted by sethk View Post
This is the exact same problem I'm having - I have a UD3P. I've tried 2 sticks of G.Skill Pi Black 6400 and Corsair DHX sticks. In combination, in alternate colored slots [to try and force single channel mode], etc etc. Will not run 2 sticks no matter what.

Are you getting a continuous series of short beeps when you put two sticks in?

I have a Seasonic S12 600W, and it's a really solid PSU that is not being even slightly stressed, so I can't believe it's the PSU...
I get no beep codes at all. My computer just power cycles over and over. It won't even get to bios screen.