Computer periodically experience issues, won't boot

[TacoBot]

This thing going on for almost half year liao. I will come home and try to on the computer, either won't boot (black screen, stuck on bios splash) or won't even power on at all. If never boot properly I will unplug power, wait awhile then plug back. Then become totally can't power up. I will try a few things like swap parts with another comp (if no one using), take out GFX, unplug all USB, try each RAM stick by stick, unplug HDD drives, but die die also won't boot. Then put back everything and wait anywhere from one hour to the next day then can boot again. Driving me nuts. I suspect mobo? but I can't be sure. Want to get some opinions on this matter...

 

[royfrosty]

State your specs that you have.

Firstly please remove the CMOS Battery and try again.

 

[TacoBot]

Keep forgetting to post specs :x

CPU & Mobo: i5-3470 & Asrock B75M-DGS
Ram: Kingston 2x4GB 1333mhz
ODD: LG DVD RW
HDD: Hitachi 2TB
SSD: ADATA SP900 120GB
PSU: Seasonic S12II Bronze 620W
GPU: Sapphire 7850 HD 2GB OC

Removed the coin battery and tried. Can't boot. Put back also can't.

 

[yusoffb01]

try use another psu

 

[TacoBot]

replaced the psu and it started spinning. might be psu.

 

[jtjt00]

In this case, jump start the PSU will fail too.

 

[TacoBot]

ok I put the PSU in another comp and the computer booted. Then I put back the PSU in the original computer and it stuck at BIOS splash. Then when I took out the computer again from its place on the shelf to check again it stopped booting again