Computer Boots up then shuts down.

[Svengal]

Hey guys, iv been having serious issues with my desktop pc, it worked perfectly but recently **** itself entirely, i boot it up and it gets so far, (password stage) then just overloads and turns itself off, sometimes dosent even make it to the password stage, sometimes further. Thinking mabey my PSU (750W) is gone? but its all new gear, i built it myself. I have i5 cpu, gtx460 graphics card, 8g ram, antec 900 case, P55A-UD3P motherboard. Also could this be caused by a damaged HDD? Any ideas or help much appreciated, any more info needed just let me know and ill see what i can do.

Thanks in advance.
Sven.

 

[MindoverMaster]

Could be many things.

First of all, download Memtest86+, burn to CD, and boot into it. If any red errors show up, it just could be your memory.

Being that you only sometimes get these, it is not your HDD.

Check for temperatures, HWMonitor, in Windows if you can stay in there long enough. Otherwise use BIOS for temperatures.

I'd leave the PSU as the least likely in this situation.