Could be memory... See if you can get your hands on another set of DDR3 memory. Past that I would start disconnecting stuff until there was only the minimum stuff connected to the MB.
If you are still having trouble then post your hardware (be specific).
I have three KHx1600c9D3K3/12GX pcs 4gb each - and I try to play with one or two....Still no luck
Also I try to minimize all stuff and still no power boot for monitor....
on MB H57M Gigabyte and i7-870 CPU (850W power supply)
On a trouble shooting page they say to test motherboard witout DDR and other drives to see if it will beep... I try.. and no beeps so they say it should beep so that is why I think it is not DDR3...
Im I right?