Anyone have any idea why this would happen? Tried installing 16 gigs of RAM (Kingston KVR1066) on this board and wouldn't boot. With just one stick of the same ram (4 gigs) it boots fine. All bios settings are appropriate for the memory. I also tried 8 gigs (4x2) of g.skill ram and while it booted it was terribly unstable until I just put one stick in (2 gigs).
Not all RAM works well with all CPUs or Mobos. I'd run Memtest86+ on each DIMM to confirm they are good. I'd also e-mail Asrock and Kingston to see if they know if this specific RAM is compatible with your CPU/Mobo or if problems have been reported. You might check their support forums also. You may need a Mobo BIOS update to resolve the RAM issue or very specific RAM to run 16 Gb. properly?
Thanks for the advice; the memory is supposed to be compatible, I intentionally bought it because ASRock said it was compatible with the motherboard. I've run the windows memory analysis thing and it says no problems; to do memtest don't you need to run it off a bootdisk? I can't even get post with all the ram sticks in.