freeze - Windows 7 freezing randomly

I have a dual boot under W7 x86 and W7 x64. Both are freezing randomly. sometimes the HDD led is fully on. Waiting only brings sometimes a black screen. here is when It freezes

• Playing a game, mostly AC


• Running chrome sometimes freeze while loading a page


• Seems it is rarer in 32 bit


• Sometimes, when I try to stop the screensaver, it is not responding (keyboard + mouse) which let me think that it froze while sleeping since I have to hard reboot since #3. Note that CD ROM reader is working.

Here is my config :

GPU: Nvidia GT 610
PSU: Antec EA-430 Green
CPU: AMD Athlon X2 64 5000+ @2.6GHz
RAM: 8 Gigs Kingston

Also, the ACPI is s1 &s3.
Finally, it seems that freezes came by session : I get a freeze after a long time and then I reboot, then I can get several freezes quickly. It makes me think it's b/c of overheating but I ran a GPU stress test and it get past 100 °C w/o freezing. Besides, according the following charts, it doesn't get past 90 - 95° C.

Here is a chart of my log while playing until it freeze (open in a new tab to enlarge):

A second one uring an other session of gaming:. I usually overclock my GPU from 810 MHz to 830 MHz but this time:

I ran a GPU stress test and it is boiling (get past 100° C) without any freeze. Stop there to avoid burning out my GPU

UPDATE #3

I removed the latest version of the nForce drivers into a lower one, it seems freezes in game are rarer.( I got one after)

So,

• What can I try to solve the freezes ?


• Is it worth upgrading my config? please use arguments

UPDATE #4

It froze while poking around in the BIOS.

I must also precise that I don't have any inverter I had one but it was dead since some times - perhaps the freezes started just after. Anyway, I bought one just now. We'll see.

UPDATE #5

I manually tested my Power Supply, it displayed 12.36 for +12V, and didn't seemed to change anything. However it seems I applied too much thermal paste on my CPU (grey one).

UPDATE #6

I cleaned the cpu and the paste but i stil got freezes...

Answer

Man, I had a similar problem some time ago, and it was driving me crazy!
So, that's what solved my problem: change the Memories of slot.

I started to think what changes I did until this problem came annoy me, and then I realize that I had bought a new FAN for my FX-8350 and I've needed to change the memories of slot because of the size of the FAN, then I turned on the PC and performed a stress test of Memory, at some point the Windows Freezes, so that were the problem.
I changed the FAN and put the memories back on the original slots, then the problem disappeared!

Hope this help! :)

Edit: This could also be a motherboard slot problem or a memory problem.