Gigabyte GA-K8N Pro-SLI ATX AMD Motherboard

GIGABYTE Geforce 6800GT 256MB GDDR3 PCI Express x16 Video Card

AMD Athlon 64 3500+ Venice 1GHz HT Socket 939 E3 Processor

pqi TURBO 1GB (2 x 512MB) 184-Pin DDR SDRAM DDR 400 (PC 3200) Unbuffered Dual Channel Kit System Memory
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pqi TURBO 1GB (2 x 512MB) 184-Pin DDR SDRAM DDR 400 (PC 3200) Unbuffered Dual Channel Kit System Memory

GIGABYTE 3D AURORA GZ-FSCA1-ATB Black Aluminum ATX Full Tower Computer Case

Antec NeoHE 500 ATX12V 500W Power Supply

My computer has worked fine since I put it together in August. I moved everything to a new case and added second two sticks of memory and the power supply in late Jan. about a month later the computer stops working, the monitor acts as if nothing is connected and the lights and fans still work. Didnt happen again for another month. Now it happens only after its been on for a few seconds. I've tried all different kinds of memory combos so I think I've eliminated that. Im going to change out the power supply next. Anyone got any ideas?

I changed out the power supply, same problem.

check your bios is your cpu overheating; is your ram bad?

I dont think its overheating because it shuts down right after it boots up. As for the memory I have two sets of 512 sticks and I've tried all the different combinations of the two sets and the 4 slots, the only thing I havent checked is each of them individually.

Check them individually. Also ensure youve plugged them in tight, and that there's no dirt on the connectors.