Consistent BSODs for over a year.

Hi All,

I built this computer in December 2009. Since its creation I have been getting consistent BSODs. BSODs occur randomly. Sometimes they occur a few minutes after starting a game (Mass Effect, SC2, etc). Sometimes the computer will be idling, and I will come back to it to find "Windows has recovered from an unexpected error," indicating a BSOD. I am almost sure that this is something hardware related, but I don't have extra hardware to be swapping in and out to troubleshoot the offending component.

Computer is homebuilt:
Mobo: Asus Maximus III Motherboard
CPU: i5-750 (running at stock speeds, has never been OC'd)
Watercooled CPU block
Ram: 4 GB G.Skill Memory (Newegg.com - G.SKILL 4GB (2 x 2GB) 240-Pin DDR3 SDRAM DDR3 1333 (PC3 10666) Dual Channel Kit Desktop Memory Model F3-10666CL8D-4GBHK)
PSU: Corsair CMPSU-850TX
HDD: 1 TB Samsung Spinpoint F3
GPU: HIS Radeon HD5970
OS: Windows 7 Home Premium X64
I am running a recent version of Norton Internet Security Suite

Any help would be greatly appreciated. Even if you can simply point me to the problematic hardware component, I can try to troubleshoot the rest.

Thank you.

Thank you for the quick response, I was out of town last week. Never occured to me to test the DIMMs one at a time. One DIMM was bad, sure enough. I also swapped sockets to make sure it wasn't a bad socket in the mobo.

Thanks again for the help.