Hi i built a new system,
cpu: q6600 2.4 ghz
motherboard: asus p5kpl-vm
memory: 2*1GB kingston 800mhz
video card: zotac 9600gt
hdd:seagate 500gb ncq sata2
case and psu: aopen 350watt

while i am playing a game, it suddenly crashes screen is freezing and white dots on it and i have to reset i couldn't go back to windows i checked my system's temperature. there are no unusual temperatures . these crashes happen sometimes playing after 5 minutes or sometimes after 30 mins or 1 hour. plz help what is the reason for these crashes

my first guess would be your psu. seems to be a heavy load for that psu, which causes more noise and ripple in the output and can lead to instability. can u list psu specs?

The 9600GT requires a 400W PSU with at least 26A on the 12V rails per nVidia. So your PSU needs to be upgraded.

so can you please advise me a new psu? which brand? but it should be cheap

how much is cheap? here are 3 options that should work, in order of price and my preference

http://www.buy.com/prod/corsair-vx [...] 52646.html
$70 AR free shipping

http://www.ewiz.com/detail.php?name=PS-VT460N
$55 + shipping

http://www.newegg.com/Product/Prod [...] 6817148027
$25 AR free shipping

thanks the first one looks fine

Anything with Corsair, Antec or Silverstone on it over 500W
The first two provided by Cold neutron look fine... the other one will probably be fine, but that 8cm fan will be noisy when the PSU heats up (depending on airflow and ventalation that could be rarely or commonly).