Windows 7: Computer shutting down

About 4 days ago my computer got a new PSU. Things are a bit better than they were ( Now it can actually BOOT WIN 7 )... BUT ( There is always a but, isn't it? ) today i installed a great game that I enjoy playing, Assassin's Creed 2. After a 15 minutes of pure fun, my computer just shut down, no BSOD, no warning, nothin'. My specs are:

CPU: AMD Anthlon 62X2 5000+ Black Edition 2.6GHz
GPU: Nvidia GeForce 9600GSO 384Mb VRAM, 128Bit
RAM: 4Gb DDR2 800MHz Kingston
Motherboard: Biostar NF520-A2 TE AM2
OS: Windows 7 32 Bit
PSU: Platinum 400W



Now any game i play my computer shuts down... Can this be caused by bad PSU, dust, high temperature or something else? Please help me.

If a new PSU helped I can only imagine that it is underpowered but looking at the spec it should be able to cope.

Have you the latest driver for your card?
And have you checked event viewer? (type event viewer into search box,try the system tab)

And also,32bit will only be able to use 3GB MAX ram,64bit will allow use of 4GB or more

Well i have a few events over here... 2 critical Kernel-Power errors ( because computer lost power ), a LOT of errors and even more warnings... Also, i know about the 32bit and 64bit "thingy", but at the computer service ( that's how you call that place where "professionals" repair your computer, right? ) they installed the 32bit version and i am to lazy to change it to 64bit...

Also, i have the latest video card drivers. Thanks for the respond!

Will changing my power plan to high performance help? I tried power saver and balanced and it didn't help... But i doubt high performance would help because then my computer would just use more power.

EDIT: Will, maybe, reinstalling Windows or maybe even removing 1 2GB RAM module help?

Can't anyone help me out?

Sorry for the double post, had to keep my thread on the first page so someone who knows how to fix this problem help me...

FWIW: I have found PC's shutting down due to heat problems, One is that the cpu cooler gets a fine mesh of dust from carpets, cats, dogs and other type hair on it. This reduces the cooling of the cpu fan and it could just shut off your system. Also, if your cpu was not installed properly, ie.. conductive grease on top to the heat sink, this could allow your cpu to overheat. Same with your video card if it has a fan on it.

Things to check.

Rich

Check your hardware components with OCCT
OCCT (OverClock Checking Tool) 3.0.0 download from Guru3D.com

OK i'm gonna check out the tool and my computer is pretty clean on the inside. Thanks for the reply!

I removed 1 RAM module ( 2GB DDR2 ) and downloaded Everest. I didn't check the temperatures... I don't know how... However, i noticed a strange detail, my cpu uses 1 core ( checked while not playing games ). Is this weird, or is it how it should be?

Go to msconfig(Start>Run), then open the 'Boot' tab, go to the 'Advanced Options' and uncheck 'Number processors'

I don't see any Max processors option here...