I have this ASUS p7p55d-e pro for about 8 months(got it last July) and for this last 3-4 days I cannot boot without clearing my CMOS.
What I have is:
Seasonic M12D 750W ASUS P7P55D-E Pro Intel Core i5 760 Quad Core Processor Lynnfield LGA1156 XFX GeForce® 8800 GT Alpha Dog 512 MB DDR3 Standard (PV-T88P-YDF4) 2x Corsair XMS3 CMX4GX3M2A1600C7 4 GB DDR3 2X2 GB DDR3-1600 CL 7-8-7-20
I tried to remove all the unnecessary stuff: HD/DVD/pci card/USB cable/etc I tried with only 1 dimm filled, instead of my 4, each one individually. It didn't work.
I tried changing the battery, here goes a few dollars to nowhere, didn't work.
If I don't reset the CMOS it sometime stock on RAM led, sometime on BOOT DEVICE led, when this happen, it stuck on CPU speed detection.
When I boot right after the reset, I MUST click on the F2 option (boot with default BIOS setting) if I go into the BIOS and save/restart, I have to reset it again When booted, everything is rock solid stable, tried memtest, CPU stress, etc, etc. Without issues.
What should be my next step? Trying a new PSU? (I need to find one.) Do RMA? (I need this mb since it's my only computer...)
Edit: I just tried with a new PSU, it didn't fix the issue.