shutdown problemm

hi, i just asked my friend to built my new computer, and i have a problem. it suddenly restart when i play a game (Farcry).

My spec is :
GE FORCE 7800 GT 256 mb DDR3
Motherboard : nFORCE4-A939
AMD athlon 64 X2 3800+ Dual Core processor
1GB RAM
XP HOME EDITION SP2
430W power supply

Can anyone help me to slove this problem ?
Thanx a lot...

Powersupply isn't giving enough juice for your monster system?

my power supply is 430W

Over heating?
Dodgy Memory?
Does it only restart on farcry?

i dontt think its overheat, becoz the temperature is only about 40C. Wat is Dodgy memory ?

Sorry I should have said faulty memory, It can cause problems like this.

Your power supply is more than enough ( I think ).
Run memtest ( http://www.memtest.org/ ) to check if your RAMs are OK.

it will always restart even i dont run anythin on my computer. how to use memtest(www.memtest.org) ? coz, after opening it w/ winrar, i dont know how to open other files...

Which precompiled distribution did you use? I suggest that you use this one : http://www.memtest.org/download/1.65/memtest86+-1.65.floppy.zip

Just extract the files using WinZIP/WinRAR to a folder and read the README in there.

i did the memory test juz now and i found 2 errors. it says pass 2 and error 2. so wat should i do now ?

juz now again i found 10 errors with 4 passes.

I really dont know wat it is...
LOL...

You have a bad memory!! Try replacing your RAM.. :(

u mean throw my ram, buy other one and replace them ? or juz plug it off and plug it in again ?

and do i have to replace them on the same slot ? or different slot ?

how many errors are allowed actually ? and the memory test won't stop rite ? so how many pass i should do ?

If memtest told you that it has found errors on your RAM, it means that your RAM is busted. You could try plugging it off and plugging it in again and re-running memtest if it helps. If there are still errors, try buying a new one.

my case has 4 slot for memory... i juz tried to put to the other slot. and the errors is decreasing... but still has 1 error from 5 pass... is it ok ? but anyway now my computer is fine....
thx for helping