help me?

ok first some specs, im using the AMD Athlon 64 X2 4200+ Manchester 2.2GHz Socket 939 Processor, ASUS EN7600GS SILENT/HTD/512M GeForce 7600GS 512MB GDDR2 PCI Express x16 Video Card,DFI LANPARTY UT nF4 Ultra-D Socket 939 NVIDIA nForce4 Ultra ATX AMD Motherboard, and Patriot eXtreme Performance 2GB (2 x 1GB) 184-Pin DDR SDRAM DDR 500 (PC 4000) Dual Channel Kit Desktop Memory,

now whats happening, ive been just using my computer for everyday b.s and its been shutting off on me, i dont get a blue screen of death just complete power off, my question to everyone is this, do you think it is the power source or i recently just enabled dual channel on my memory but the voltage is low on it, right before the computer shuts down it seems to slow down slow like its lagging then off.

What are your temps like? It could be shutting off from overheating.

CoreTemp:
http://www.thecoolest.zerobrains.com/CoreTemp/

nothing over 50 c, even the video card is runnin high 40s

Have you searched through the BIOS making sure any auto shut down features are set properly? What PSU are you running?

Sunbeam PSU-CGMI450-US-SV ATX 450W Silver Tri Mirrored X-Plug Modular Power Supply 100V~120V/200~240V, its not an expensive power supply but im not over clocking my computer right now anyway so it should be enough, i have taken out my ram, reseated it and put the voltage up to 2.8v. It has made it though the night with out a shut off so im keeping my fingers crossed but it shuts off sporadicly i have seen it stay on 4 days with the screen savers then i go to open firefox and black screen!

ok never mind the voltage bumb did nothing, it still shuts off. I was in the bois making sure all my settings were correct and it shut off there too so im guessing it has to be the psu?