Comp crashed...3 long beeps and shut down upon start up

hey guys...heres the deal

i was playing call of duty, had been playing it for weeks at this point..no problems
all of a sudden the game freezes then crashes
turned the comp off and on..played again...freezed the crashed

this time, i turn the computer on, i get 3 long beeps, each about 15-20 seconds long, then it shuts down

i took out the vid card/hd/everything, each time it gave a diff beep error so after trial and error i concluded it was the ram
i have an asus mother board, and 2 1gig sticks of ram
i moved them around, eventually got the computer to boot up, but it only stays booted for maybe 30 seconds then shuts down
itll start loading windows...everything, then it shuts down

i ordered new ram, 2 2gig sticks, put them in (left both old ones out), and the same thing happens

whats wrong with my computer!!!?

heres my original set up:
ASUS P5N32-E SLI LGA 775 NVIDIA nForce 680i SLI ATX Intel Motherboard - Retail

BFG Tech BFGR88768GTXOCE GeForce 8800 GTX 768MB 384-bit GDDR3 PCI Express x16 HDCP Ready SLI Supported Video Card - Retail

OCZ ATI CrossFire 2GB (2 x 1GB) 240-Pin DDR2 SDRAM DDR2 800 (PC2 6400) Dual Channel Kit Desktop Memory Model OCZ2A8002GK - Retail

Intel Core 2 Duo E6600 Conroe 2.4GHz LGA 775 65W Dual-Core Processor Model BX80557E6600 - Retail


this is the new ram i bought and replaced:
CORSAIR 4GB (2 x 2GB) 240-Pin DDR2 SDRAM DDR2 800 (PC2 6400) Dual Channel Kit Desktop Memory Model TWIN2X4096-6400C5 - Retail

i am running windows vista ultimate (upgrade) 32 bit

Thermaltake toughpower W0103RU 600W ATX12V / EPS12V SLI Certified CrossFire Certified 80 PLUS Certified Active PFC Power Supply - Retail

bought it in 07 with the rest of the parts

ive been looking for 3 long beeps, didnt see anything in the manual about that

it just occurred to me it might be 1 long beep and repeats?

i figured it was memory, but even after i replaced the ram it did the same thing

is there a way to test if its the motherboard?

for how long your pc stays on before shuts down ? it got this problem before once with mine (after 15~20 mins on working well it just shutted down) and it was not the mems, it was the cpu was getting heat and the coolling system was not working well.
so i used artic silver 3 between the cpu and cooler and i fixed the problem.

the pc will stay on for no longer than a minute before it shuts down

im not certain if its the power supple...the computer boots up, goes through the loading screens, starts loading windows and will get to the login and as im typing in my password it shuts down

i figured it could be the ram, not having enough to run vista, but it seems that wasnt the problem

when i start it up i dont smell any burnt stuff and ive tried starting it up countless times

so im thinking its the cpu or the mother board

but again, why would 1 of these just stop working because of call of duty? there were no other signs of a problem