computer crashing?

[pinkfloyd2004]

hi people
my set up is-
Win xp home sp1
AMD Athlon 1.4 (ep-8k7a mb)(ACPI)
300w psu
512 ram
gf 2 mx 100/200
Fujitsu 20g hd
Maxtor 20g hd
Creative CD-RW
LG DVD-ROM
Modem (intel ham data fax voice)
Creatve sound blaster 5.1
All drivers are installed (upto date)

Play a game for about 15-30 mins,then the system is still running,but the monitor goes into stand by?
the pc is makeing a high pitched buzzing sound.(i thought it was the RAMDAC on the gc).it did this on the first graphic card (gf 4 ti 4400) i had,now i`v changed it for a new gf card,and its still doing it?
its not heat ,running at 45c (cpu)
so can it be my psu (300w)?
or is my mb given up the ghost?
thanks for your help
dean guilder

[dumdum]

I would Check Your Power Supply carefully. Your suspisions might prove to be true!!!

[dumdum]

Also do a Deep Scan of your hard disks

[pinkfloyd2004]

thanks for your help dumdum
plus what sort of program should i use for a deep scan?
just use the error checking pro thats comes with xp?
thanks again

[dumdum]

Yeah XP Scandisk. do a Thourough scan though not deep sorry!!!