Help!!! Computer randomly shuts off, can't figure out why

[packersmaverick]

mobo: intel D945Gcpe
RAM: 2GB of Patriot Signature pc5400 DDR2 667mhz
Processor: Intel Pentium D 925 3 GHZ
Hard Drive: Seagate 160 GB Sata
PSU: 480 Watt Sata, Came with Diablo x-man gamer case from Tiger Direct.
Intergrated Video Card

Alright I have just newly built my own computer. I bought everything but the heat sink from tiger diect. It worked fine for almost a month and now it has started shutting down randomly. It can happen whenever. I need some help.

 

[pdyckman@comcas]

The CPU 925 3GHZ may be running hot. The maximum allowable temp is 63.4 C. = 146.12 F. Get a temperature monitoring program that will keep you aware of the temp. Try "Everest Ultimate" &/or "PC Wizard". If your CPU gets too hot, it will shut down. It's the first thing I would check. If they're fastened down snug. Reseat it if it's running hot and use "Arctic silver 5" thermal grease. G'Lck.

 

[packersmaverick]

tried it

i know it aint running hotter than 45 C ive checked it dozen of times. and it happens when i aint even doing much. it restarts even when doing things like printing a document