Computer random shut's down

[xXTomXx]

First of all. Yes i know its alrdy topic like this one. i read them all.
This is my problem. Last week my computer was randomly shutting down. Wait around 5 min then turn it on again, sometimes unplug the power cable. then it works for hr's. But then one time It went off and dint get on. so i let it cool of for a day. When i turned it on it dint last more then 1 min.
To make this short. My cpu fan is clean. all the wires are on. Hardrive is fine.
When my computer shuts down the "lamp" next to my powerup and reset button Blinks. and it wont start at all. Now the computer dont last 10 second in windows.(if im lucky)
I tink it may be the powersuply. But before i go and buy one and one part for the computer i wonder if someone may tink its somting else. Cpu motherbord ram.
Btw sometimes i cant get passed BIOS so i dont tink it can be a virus.
Any help is thankfull

 

[Route44]

It would be very helpful if you could supply your system specs including make, model and wattage of your power supply.

 

[xXTomXx]

It would be very helpful if you could supply your system specs including make, model and wattage of your power supply.

* 336475 - MSI P35 NEO-FI, P35, Socket-775, DDR2, 1333FSB, ATX, GbLAN, Firewire, PCI-Ex16
* 344667 - Crucial DDR2 PC6400 2048MB CL6, Kit w/two matched DDR2 PC6400 1GB CL6
* 338081 - Intel Core 2 Duo E6550 2.33GHz 1333Mhz Socket LGA775, 4MB, BOXED w/fan
* 303162 - Antistatic Armchain 1,8m BW-106BL-L4


Powersuply:
ATX 12v Model: HPC-360-202 CHIEFTEC
Ac input:115v 8a
230v 5a
Frequency: 50-60 hz
MAX LOAD: 360w

its 4-5 years old

soundcard
aureon 5.1 pci

windows xp SP3



This is evryting i know.
And one more thing i forgot to say. The soundcard inside the motherbord stoped working. thats why i got a new sound card in it.



So what i tink is its motherbord problem or powersuply. or cpu thats burned out. But since the pc shutdowns wont last 1 min in windows idk anymore