Details of computer listed at end.
Earlier today I was using my computer for simple low-performance tasks (browsing internet, not even watching videos just reading news). It was on for about half an hour before it appeared to switch itself off, by that I mean the screen went black, there was no sound from fans or disks, and the light for the shutdown button was not on. There was no Blue Screen of Death, it was instantaneous.
I attempted to start the computer by pressing the shutdown putton, which did not seem to change anything.
I pressed the reset button (the instant-restart without correct shutdown reset, not reset as in restore factory settings) to no apparant change.
I pressed the shutdown button again, no change.
I switched the power for the computer off, and then switched it on again, and once again was unable to start the computer.
I unplugged all unnecesary external devices, and attempted to start again to no avail. This doesn't include internal unnecesarry devices.
I stopped all possible noise in my room, switched off power, switched on and opened the PC case. The motherboard's light was on, and so was my mouse's light (which is usually on if my PC is plugged in even if not running). Listening extremely carefully there was no sound, then when I pressed the shutdown button there was a VERY QUIET buzzing noise (that was inside the case somewhere but couldn't place where). Pressing the reset button didn't stop the buzzing. Pressing the shutdown button didn't stop the buzzing. Holding the shutdown button for a few seconds stopped the buzzing, and then pressing the shutdown button once started the buzzing again.
To reiterate, the front power light doesn't turn on. My monitor recieves no input from the DVI cable.
At this point, I'm slightly concerned either my processor or motherboard is broken.
If anybody could help diagnose what's broken or what's causing the malfunction that would be much appreciated.
ABOUT THE COMPUTER (specs/history):
Motherboard: Asus P7P55D-E LX
Power: 470 Watt
Other specs are in 'specs' of my profile listed under 'Main Computer'.
Computer is all 1st-hand parts, assembled 1.5 years ago.
The processor and RAM has NOT been overclocked.
Temperature was typically listed as roughly 35*C in all components, roughly 40*C after playing certain games for extended periods of time. Exception was one component (I think it was listed as AUX1 or something) that I'm not sure what it was at all and apparantly ran at a constant 83*C, which seemed rather arbitrary as it would be like that all the time (seconds after boot to hours after use). I was told to ignore this as apparantly this temperature, if correct, is still not too high if it never changes.
Changes made have been addition of 4GB RAM a year ago with no noticable problems since (to make it up to what it is now).
Addition of a second 1TB HDD, also 7200RPM (not listed in specs), about half a year ago with no issues. I have run OS's from both hard drives at different points in their current positions, and no errors have been shown to me recently.
About a year ago my computer was continuously using about 25% CPU usage according to Windows, which was discussed here:
http://www.computerhope.com/forum/index.php/topic,129713.0.htmlThe conclusion was that it was a software issue, the solution was to reinstall Windows.
