PC Crashes after trying to do something minor

[PapaShand]

My PC crashes after trying to carry out tasks such as downloading files or running csgo matchmaking but i do not know the problem. It will work, then suddenly stop after 5 minutes then keep trying to reboot and fail to turn on until you tell it to stop!

Does anyone know for certain why this is happening?

My specs:

Case: CiT 1017 Black Midi ATX Mesh Gaming PC Case (Not Functional Currently xD)
Motherboard: MSI Micro ATX G41M-P25 LGA 775
RAM: 2 x 2gb Rendition DDR3 240 Pin 1333Mhz
Graphics Card: Nvidia Asus GeForce GT 730 Silent 1gb
Processor: Intel Core 2 Duo E8400 @3.0Ghz
Power Supply: CiT Pemtium 500 Watts 230 Volts Micro ATX
Hard Drive: 160gb Seagate Barracuda 7200 RPM SATA Main HDD
320gb Western Digtial Caviar Blue 7200 RPM SATA 2nd HDD
Portable Verbatim 500gb External HDD
Fan Cooling: 1 x 92mm CiT 7 Blade PSU Fan
2 x 120mm Arctic 9 Blade Side Vent Fans
Operating System: Windows 8.1 64 bit Pro

I can provide more detail if needed to solve this, fire away!

Thanks.

 

[InvalidError]

If the PC randomly goes into boot-looping, the problem is often a failing PSU - especially when junk-quality brands like CIT are involved.
http://www.tomshardware.co.uk/forum/id-2547993/psu-tier-list.html

So I would start with replacing the PSU with something decent, tier three, preferably two or one if possible depending on what is available to you.

 

[boosted1g]

Agreed that a junk CiT psu would be the first suspect.

You cant expect your PC to run stable when its voltages are not stable, even at light load.

 

[PapaShand]

If the PC randomly goes into boot-looping, the problem is often a failing PSU - especially when junk-quality brands like CIT are involved.
http://www.tomshardware.co.uk/forum/id-2547993/psu-tier-list.html

So I would start with replacing the PSU with something decent, tier three, preferably two or one if possible depending on what is available to you.

What do you think of this?

http://www.amazon.co.uk/XFX-Edition-Bronze-Wired-Supply/dp/B005FPT38U

Thanks for the help so far.