New build keeps restarting on cold boot unless CMOS is cleared.

I recently built a budget gaming computer but am having issues with it powering up. I push the power button and the fans and lights turn on for about 1 second then everything powers off and it continues to restart itself doing the same thing over and over again. At first it would only restart like 3 or 4 times and then would proceed to boot up with no problems, but now its been restarting itself for like an hour without booting. Yesterday it did this, so I unplugged it and removed the CMOS battery and put it back in, and this solved the problem temporarily... I was able to use the computer for the rest of the day without any issues. However, this morning the problem has returned (powers up for like 1 second and then turns off for 3 seconds, then starts again).

The weird thing is that if I am able to get it to boot, it runs all my games well without any shutoffs or restarts. The only issue is getting it to POST. But once that happens, everything runs great.

I have removed the video card, replaced the ram with sticks that are known to be working, and removed everything that could cause an issue but the problem still remains. At first I thought it was the power supply but after seeing the computer work right after clearing the CMOS I now think its the motherboard.

My specs:
Intel Pentium G2020 @ 2.9 GHz
XFX Radeon 7870 not OC'd
AsRock B75 motherboard
Rosewill 600w power supply
temporarily using a 4GB stick of ram from my main rig since my 8gb kit hasn't arrived yet
intel stock heatsink
Seagate 500gb 2.5" laptop drive
no optical drive


I know my PSU isn't great but it was in my friends computer for a year without any issues so I don't think its the cause. I'm pretty sure its the motherboard, should I try to return it or is there something I can do that could possibly fix things, like a BIOS update or something? Maybe my newly released G2020 isn't fully compatible??? I'm reluctant to return it because like I said, it does work sometimes.