Likely problem- mobo, power supply, OS?

[Chamois]

Hello,

This morning my rig is completely dead and I need a little help figuring out where to start. About 3 weeks ago my machine started having problems waking from sleep- sometimes it would not respond (fans would come on, no mouse, keyboard, or video though), sometimes it would take a press of the reset button and resume Windows 7, sometimes it would require an unplug and a complete restart. I can't tie this with any specific occurrence like a new Windows update or anything. No new hardware was added either- everything is exactly the same as when I bought it 2 years ago.

I did a little research and checked the power profile, updated the BIOS, and updated the video and mouse drivers. Nothing got better. I finally disabled all sleep/hibernate options and left the rig on 24/7.

Over the last week, the three times I've purchased something on iTunes the program has alerted me that an unknown machine was trying to access my iTunes account and it made me go through the whole security check with re-entering credit card info. (Does a failing motherboard somehow lose the ability to identify the system?)

Finally, last night I left the rig on and when I got up this morning it was totally shut down and unresponsive to anything- power button, reset button, unplug, etc. It's just dead.

Any thoughts on what I should look at first? This was my first build and I know barely enough to be dangerous, but my suspicions are in this order- motherboard, power supply, operating system/hard drive. How should I go about troubleshooting this?

Specs:

i7-920
ASUS P6T
Silverstone ST70F 700 w power supply
OCZ 6 GB memory
WD Caviar Black 640 GB
EVGA GTX 275
Windows 7 64-bit

Thanks for reading this, any thoughts and ideas are appreciated.

 

[mcnumpty23]

if its totally dead i would check the power supply first--you can do it using the paper clip trick here

http://aphnetworks.com/lounge/turn_on_psu_without_motherboard_the_paperclip_trick

if the power supply fan doesnt spin then its either dead or the fuse has blown

if the power supply is ok i would say motherboard

operating system fault wont stop power going through you just might not get to windows or get blue screened is all

same with hard drive--never had a faulty hard drive stop all power going through

 

[Chamois]

Ok, thanks for the fast response. I'll give this a shot.

 

[Richard226]

If you are going to be into building your own computers then a power supply tester could be a worthwhile purchase.

 

[Chamois]

Thanks again for your help, I tested the power supply using your suggestion and it seemed totally dead. I ordered a new Seasonic unit, hooked everything up, and hit the power button...the system sprang to life and all appears to be working normally. I really appreciate the response.