I purchased one of these motherboards about four months ago. I have been having problems, it's been off more than it's been on. I have updated the BIOS to the latest version. I have put in new power supplies, changed cases all to no avail. The damn thing will not turn on unless it wants to. And yes there is thermal paste on the CPU. This ain't my first rodeo. I'm also getting tired of having to short out the ATX connector for he motherboard to come on. In fact yesterday even that didn't work. I'm curious if there was anyone else having this problem with this motherboard?
Few things for you to try, if the Bios chip on the board is in a socket, try pushing it with your little finger in the centre.
Sometimes if it has slipped out it causes the computer not to boot.
Have you also checked that none of the back side solder points of the board are not touching the back plate where its is mounted in the case, a short can do this, Ie a miss placed stand off where the board does not need one but has been left in.