Sudden shut down problem after not being turned on for 2 months

[cubex]

Hi guys, I have this PC with this spec:

RAM - 2x kingston 2GB DDR3
VGA - NVIDIA GeForce GTS250
MB - GIGABYTE S-SERIES GA-P41T-ES3G
CPU - Intel Core 2 Quad CPU
PSU - SimCool 430W

My problem is that my PC starts to give me sudden shut down problem. no warning, no nothing, just shut down like when we pull the power plug.

I went to the shop where I bought this PC to check for any hard drive error, and they said nothing is wrong with it. they gave me a new power cable, the PC lasted for a 1 or 2 days without the problem.

And then now it started to give me this problem all over again.

Any comments or speculation on where the problem is?
anything i need to know to fix this?

Thanks for the help guys =)

 

[Ritwik7]

It could be any number of issues. What are your system temperatures? Sudden shut-downs can be caused by an overheating CPU.

Use HWMonitor to check your temps. If they're under control then it may be a problem with the PSU.

 

[cubex]

the cpu temp after the shut down is only 37 degree. system temp is 30 degree

 

[Ritwik7]

After the shutdown will give no indication. You'll have to see what the temperatures are like just before your PC shuts down.

 

[raybay]

Replace that SimCool PS with a good one, such as Corsair, FSP group, Sparkle, Antec, OCZ, and I'll bet the problem goes away