Pc problems if anyone could help id be grateful

hi quick computer question for you.

my pc keeps switching itself off, ive checked in the bios and its making a error sound when i turn on the warning for the power fan, im guessing this is aimed at the power supply?

i know this probley sounds noobish but i wanted a 2nd opinon before i just went out and brought a new one.

so do you think my power supply is faulty as it works when it wants to.     
windows doesnt report any errors and assumes its been shut down properly,  
hope this helps.

Have you got the manual for the motherboard? If it's making a beeping sound pattern when you turn it on, the motherboard manual should list what the patterns of beeps mean, and then you could tell what the issue was, maybe.

About how old is the power supply/computer?

"Have you got the manual for the motherboard? If it's making a beeping sound pattern when you turn it on, the motherboard manual should list what the patterns of beeps mean, and then you could tell what the issue was, maybe. "

" Self shutdown mostly indicates a thermal problem. Try dusting the interior of your computer and check the connections the cables have with your mb and the components. "

" @SinGulaR said:

" Self shutdown mostly indicates a thermal problem. Try dusting the interior of your computer and check the connections the cables have with your mb and the components. "

This. Check your fans. "

Install Speedfan to check your core temperatures.  This definitely sounds like a thermal problem.   
 
Is the PSU fan actually spinning?  There should be some air coming out the back of it.  If there is no air movement out the PSU then I think you've found your problem.

Make sure the heat sink is making good contact with the cpu and tighten any screws on the bracket. Also check that the fan is working on the Psu

"Make sure the heat sink is making good contact with the cpu and tighten any screws on the bracket. Also check that the fan is working on the Psu " 
 
the heatsink im using is a Stealth samurai one of the older models now and its compounded propely id assume.

"Install Speedfan to check your core temperatures.  This definitely sounds like a thermal problem.    Is the PSU fan actually spinning?  There should be some air coming out the back of it.  If there is no air movement out the PSU then I think you've found your problem. "

"In that case there may be in fact a problem with your power supply. Sophisiticated ones have a fail safe which shuts  them down in case there is a problem. But most of the problems that come up with a power supply are thermal as well. You should troubleshoot by removing uneccesary components like disk drives ore other hardware that isn't vital for your pc to boot up and check again. If the issue persists you will probably need a new power supply. Damn... it's saturday and I'm working on my free time... who is going to pay for this? :D "

Going out on a limb here and saying it could also be faulty RAM.

"Going out on a limb here and saying it could also be faulty RAM. "

Pretty soon you're going to have extra PSU's around like me to test these things.  Thats when you know you've leveled up as a nerd.

" @Detrian said:

"Going out on a limb here and saying it could also be faulty RAM. "

its probley not 100% accurate but i used a ramchecker and ive tryed 2 sticks of 5300 1 gig as im running 2 2GB sticks of DDR 2 6400 "

" Pretty soon you're going to have extra PSU's around like me to test these things.  Thats when you know you've leveled up as a nerd. "

" @mattbirdy1986 said:

" @Detrian said:

"Going out on a limb here and saying it could also be faulty RAM. "

its probley not 100% accurate but i used a ramchecker and ive tryed 2 sticks of 5300 1 gig as im running 2 2GB sticks of DDR 2 6400 "

Oh yeah if you've completely replaced ram then that's not it. It could also be a video card issue or your stuff overheating. Do you have windows set up so it throws up a blue screen instead of just resetting the pc when something goes wrong?   Well whatever it is you could try taking it to a repair shop or checking if someone you know has a power supply to test. "