I had an ASUS P8H61-M with an i3-2120 CPU. This setup ran just fine, but recently a friend of mine gave me a variety of i7-3770s/i5-3570s to test to see if they worked. I had to update my Motherboard BIOS for these chips to be supported, so I went ahead and updated the bios. After that I rebooted the PC to ensure the new Motherboard bios worked okay, and everything booted just fine. Then I started trying the CPUs my friend gave me and all of them exhibited the same symptoms:
Black screen on display.
GPU fan spins up, stops spinning, then spins up again
No beeping from motherboard speaker
I've tried removing the GPU and using the onboard video, and I get the same problem
I figured all of the CPUs must have been dead, but now when I try my known working i3-2120, I am getting the same issue. I am stumped. I tried clearing the CMOS/RTC with the jumpers, but I have no way of knowing if it worked or not due to the black screen. Any help/advice is greatly appreciated. Thank you!