Weird problem

Hi guys!
I got my new MB it's an ASUS M5A99X EVo r 2.0. I got this new MB because of having problem with the old one (thought so). I had a BSOD after starting the system was turned on for the first time (it was off over night). When I turn on my pc after couple of hours being off (6-7) I got this BSOD every time. So I just have too turn it off and start it again. After that no BSOD. So I ran the memtest after the pc was turned off for a longer period and it shows 42 errors in test num.8 and over 200K errors in test num. 9 but it was still counting (I shut it down). This all was happening with my old MB Gigabyte GMA 880 UD2H. I thought the memory slots was corrupt. But now I now the problems is somewhere else. Its maybe crazy I know but it doesnt work when the pc is off for a longer time. Every day is the same story. I dont know what to do is the PSU? RAM? CPU? please help

RAM: Corsair 2x2GB 1333MHz tw3x4g1333c9a
CPU: AMD Phenom II X4 840 3,2 Mhz
PSU: Seasonic 620 watt
MB : ASUS M5A99X EVo r 2.0

I tried tweaking the RAM in BIOS, setting the timing to 2T, lowering latency and frequency, changing the voltage but with no result