New build error system shuts down after 20-45s

[Aetherynn]

ok here goes i just finished building a new system from the ground up, Asus P5B board processor is an intel core 2 duo 2.66mhz i have 2g ddr2 800mhz memory, radeon HD2600 pro Vieo card, new SATA HD and cd/dvd rom drive i go to boot up to run the startup disk for the new hard drive and whether i go into bios or let it try to boot from the CD the comp just shuts down, ive rechecked all cables/jumpers/fans and everything seems to be in order yet still it kills after 30s or so. any ideas would be greatly appreciated thanks!

 

[Daveskater]

• what power supply have you got
• did you put good thermal paste on the cpu heatsink and apply it properly

p.s. your cpu will be 2.66ghz not mhz otherwise it'd be about 15 years old

 

[Aetherynn]

its a 550w supply and i did use a thermal paste im not @ home atm so i dont remember the brand name maybe i should clean it off and try a different one?

 

[Daveskater]

it wouldn't hurt to put arctic silver paste on, make sure you only apply a thin layer to the cpu

does the pc shut down as soon as you try and go into the bios or a few seconds after?

 

[Aetherynn]

either wway it shuts down if i go into the bios bout 20s or so it shuts down or if i just let it sit it does the same thing.

 

[aspirulito]

you can also try a different PSU, sometimes they come broken from the factory and it sounds like a problem I just troubleshooted in a brand new computer, and it happened to be a spanking brand new (620 W) broken PSU.

 

[Aetherynn]

well i put a different thermal paste on and she seems to be staying on now ty!

 

[Daveskater]

i'm glad to hear you got it fixed

i expect the old thermal paste wasn't very good or wasn't applied properly so the heat wasn't getting through to the heatsink properly so the cpu got hot quickly and shut itself down