PC not posting all the time

[halopcdraco]

I'm not sure which category to put this in. This has been the most dumb founding problem I have had with this computer. One day I turned on my computer and the monitor stayed in stand-by mode. So I tried the monitor with my laptop and it worked, so it's not the monitor. I tried switching out my graphics cards and only using one. I thought it was my CPU. So i bought an 8 core CPU. I did a memtestx86 on each ram stick on a few passes and one stick didn't make it through one pass. After that, my computer has ran fine for a few days. Then all of a sudden, my computer froze. Went to turn it back on and it didn't post again. I turn off the psu, then on, turn on the computer and it posts and i'm able to get on my computer. If i restart the computer, it doesn't post. If I shut it down and then turn it back on it doesn't post. To make things easier i'll post my computer specs:

Motherboard: Asrock fatl1ty 990fx professional
CPU: AMD FX-8350 8 core @ 4.0 GHz (not overclocked)
RAM: AMD (by Patriot) 4GB DDR3 @ 1,333 MHz x3 (was x4 but that one is faulty)
Graphics: XFX AMD Radeon HD 7770 1GB DDR5 128bit @ factory 1095 MHz
PSU: Thermaltake Smart Series 850W Modular
Case: NZXT Phantom Full Tower Red
OS: Windows 7 Ultimate
HDD: Kingston V+300 120GB SSD (main), Intel 330 Series 240GB SSD (for games), WD Green 320GB 7200 (other programs)

 

[halopcdraco]

Seriously? Everyone else's post gets some kind of answer, but when I post something, I get shit.