I've had this no post red CPU light / restart cycling problem on a combination of two CPUs (i7 2600k) and 3 ASUS MBs (regular, evo and sabertooth). [16Gb Vengeance RAM, 570 Graphics card]
First board p8p67 regular - no post (tried everything for about 4 hours). Took it to my local low end repair shop; they tried everything including flashing the BIOS told me that on another board everything worked so I got another board.
Second board EVO - posted first time. It was all running great for a while, so I tried to overclock it to 4Ghz (a conservative first overclock): all the temps were fine while running prime 95 for about 30 mins. Then the screen went black and we were back to the red CPU light 1 second boot cycle again... Tried everything again and again nothing worked. I really need a decent machine at home for work, so I went and got another board and CPU.
Third board sabertooth + new i7 CPU. Posted and then crashed in the BIOS setup.
I want to qualify this by saying at this point that I think that all of the parts probably work individually. But together there is something odd going on.
I've build and clocked my machines for the past 5 years and have never known anything like this; a CMOS clear always gets thing up and running again.
I've wasted about £450 more than I had planned to spend so far on trying to get this rig working; not to mention the time and stress of it.
Finally I've got to the stage where I'm taking everything I've bought to a good computer shop that specialises in high end parts and am swallowing the cost and pride of them building it for me.
So the point of this post is basically to say: If you have an ASUS p8p67 board that is red light cycle booting (I guess you do as you are reading this forum).
1. First try everything like clearing the CMOS, booting with one stick of RAM, etc... for an hour or so.
2. When that doesn't work pack everything up, swallow your pride and go to a good computer shop and get them build it for you. This will save you both time and effort in the long run.
That might sound a bit defeatist, but there is just something incredibly flakey about these boards and I wish someone had given me that advice two weeks ago.