New PC shuts down a few minutes after power on

[triumphtriple]

Hi all,
I have just installed the following into an old Trendsonic midi case and the PC keeps shutting down while I am in the Bios menu (have tried different power leads):

ASRock FM2A55M-DGS R2.0 mobo
AMD Trinity A8 5600K 3.6Ghz CPU
Alpine 600W Gold SLI Crossfire PSU
2 x 2GB DDR3 1333 RAM modules
Western Digital Sata HDD
Optiarc DVD drive

I have 1 x chassis fan fitted and a bog standard CPU cooling fan. I'm guessing my problem may be temperature related but am open to suggestions as am starting to go slightly nuts!
Thanks.

[Canker_Canison]

Did you paste the processor/heatsink correctly?

[Cod3waX]

also are u using a separate gfx card or onboard?

do u flash a blue screen before it powers off? try using only 1 ram module at a time

[Reapers]

if its new and from a shop take it back and they should fix it for you.
if not then try the basics
does it actually shut down or go into sleep or hibernation?
how long is it before it shuts down is your case well vented ?
does your cpu have paste on it your cpu fan hooked up to power?and working? is it just in your bios settings that it shuts down like that
did you overclock it or put it in to turbo mode because that can cause heat and i don't think standard cpu fan would be able to handle it

unplug the pc
check wires outside case
check the wires inside the case *especially the molex connectors make sure the power is off when doing this*
take out any new hardware including usb except keyboard and mouse (be careful)
check the ram (1 at a time)
graphics card (if the monitor boots its fine it's very rare to be hardware on a graphic's card because they decently built
if it was a hardware issue most wouldn't boot the operating system and the monitor would not come on.)