Blue screens and crashes - I need help figuring out why

I've been getting some blue screens and crashes lately on my newsystem. Here are the specsC2D E6600
Gigabyte 965P-DS3
4GB (4x1GB) PC6400 DDR2 (4-4-4-12 @ 2.1v as per spec)
nVidia 7950GT
Creative Xfi
500GB HDD w/16MB cache
DVD Drive
DVD R/W Drive
500W Ultra Xfinity PSU
1 120mm fan
Vista Home Premium 64-bit3 USB devices connected to system at all times (kb, mouse and mem-card reader). Everything's stock, nothing's overclocked.The problem started when I installed Company of Heroes. Sometimes it would freeze/hang on me, in which case I was able to CTRL-ALT-DEL and close it out. Other times it'd send me to a blue screen. The blue screen lists some memory addresses (looked like it was displayed on hex). Now it does this even when I'm notrunning a game.I recently installed 2x1GB of memory into my system. So now the question is, what's causing my system instability? I've come up with a couple of ideas1) Overheating. I only have 1 120mm fan in the rear. I felt around my system and nothing seems to be running especially hot save for the RAM modules. Since all my RAM slots are filled, there's not much space in between them. Each stick of RAM has a heat sink on it too so that may be contributing towards overheating the memory.2) Bad memory. I had just installed new memory in my system and priorto that, it was running nice and stable3) Insufficient PSU. Even though I have a 500W PSU, it's a relatively generic brand. It may not be able to supply my system with enough juice under load.So what do you guys think? I just pulled out my newly installed memory and am testing my system now for stability. Anyone have any other suggestions should this not solve the problem? I may just end up having to buy another 120mm fan for the front of my system.Blue screens and crashes - I need help figuring out why
Run core temp, speedfan, Intel TAT, or something and find out what your temps are. But considering this started after adding more ram, that makes me suspect ram too.Blue screens and crashes - I need help figuring out why
First of all, I like how you told us everything we need to know (wish everyone was like that on here). As for the problem, try putting your old memory in and if that doesn't work, put back your new memory and if you have an old PSU sitting around go ahead and try that. Or you could also try using the computer with the side panel off to let out the extra heat.
What's the error code displayed on the Blue Screen? Sometimes a Stop Error can narrow down the problem to hardware or software, even a specific piece of hardware or software. Checking the Application and System portions of Event Viewer for errors and / or warnings can help narrow the problem down as well.
Im thinking it is the memory.what kind of memory do you have (brand, model #)