A few days ago, I put my computer on standby, and instead, it seemed to shut down. I did not have hibernation enabled, so when I turned it back on, I tried to see if I had turned hibernation on by some accident, but instead, couldn't even find the option for hibernation to turn it on or off. The options for standby and shutdown options had not been tinkered with, so everything seemed fine. A little paranoid, I did a virus/spyware/etc... scan and found my computer to be clean. So thinking that maybe it was a glitch, I ignored it. But when I tried to put it on standby yet again, the same thing happened. I decided that I would do some research on the issue, but couldn't right away, so I decided to turn my computer off and come back to it later. Today, however, when I got back to tinker with my computer, I hit the power button, and nothing happened. It wouldn't turn on no matter what I tried. I tried unplugging the cable, tried turn the powersupply swith on and off, even clean up the inside a bit. It seemed nothing would fix it. I checked the fusebox, but everything else was working fine and the fuse was fine too. When I put my ear close to the back of the computer, I can faintly hear the power supply whirring very very quietly. When I unplug the cable or switch it off, it begins to die down and goes quiet, and when I replug it or switch it back on, it starts to slowly make the same faint whirring sound. I'm on my laptop right now, and hoping someone has some knowledge on this issue and how to fix it. I was told maybe it was the powersupply went bad, or the button broke or something. I would like to take it to the local geek squad nearby tomorrow, but don't know if they can help me. I shouldn't need to replace anything as this custom built computer is only a year old and only recently has had some problems (blue-screen shutdown due to a faulty windows update (I thought it was fixed but maybe this is the issue) and the recent standby glitch now to it refusing to turn on no matter what). Any help would be appreciated.

My specs;

Windows XP Pro x64 Bit Edition
AMD Athlon 64 X2 Dual Core 4800+ Socket 939
4096MB DDR400 PC3200 Memory (Kingston) (1024MB x 4)
ASUS A8N-SLI Premium Motherboard
Western Digital 500GB 7200RPM 8MB (each) Cache Serial ATA II (250GB x 2)
ASUS EN7800 GTX Ultra PCI Express 256MB DDR3 x 2 SLI
Creative Sound Blaster Audigy 2 ZS Gamer 7.1 (recently this has begun to glitch on me as well)
680 Watt Thermaltake Power Supply Dual Fan
ASUS 16X DRW-1608DVD RW +- Dual Layer

This really caught me offguard and is really upsetting. Hopefully, with your help, I'll be able to resolve this issue. Thanks in advance.

Although it is great to hear that the computer you own is custom built, that does not mean that it is invulnerable to failure do to that fact or it's age. There are a million things that can go wrong with a computer. My first idea (although it is likely you have checked this through) is to check your monitor. It is hard to diagnose a problem like this. Unplug everything from the monitor to your keyboard and anything inbetween. Also make sure that everything is green at the multi-port plug, and the electrical outlet. Use a device that you know works to test all the ports to be absolutely certain that it isn't an electrical failure. Next open your computer up and make sure that everything is tightly set inside of your PC. When I say everything, I mean everything, from the hard drive cables to the video card, they all must be well set in there own pci/agp/pci-e slot, and also check the processor. After you are certain that all of everything is right inside of the computer then you may also want to test your monitor on your laptop, there should be a blue plug on the back. Once you have gone through all of those steps, then it is likely you have a form of hardware failure, it is pretty well impossible for me to tell you anything from here if I cannot see the computer. If you have any further questions, like how to mess around with the inside of your PC or anything else, feel free to ask. Good luck!

Hi Solo, welcome to the PCHF!
Your computer is almost as good as mine (my CPU has a larger cache size)...and I have better video..and a 150gb raptor....but that's it, everything else is the same/you have better

It might be an idea to reset your BIOS before attempting all that Brad suggested. Pull the power cord out of your computer, leave the power supply switch turned to the on state. Now, with the power cable out, press the front power button 5-10 times. Reinsert the power cable, and try booting now.