How to diagnose hardware problems

Is there a rule of thumb method for diagnosing which components may be fried if your PC does not start up? I have a newish PC I got from one of those eBay store resellers (cowboom) that will not boot up when turned on and would like some help in figuring out where the problem lies. Here is the problem I have been having:

PC was completely functional one day, then powered down normally in Windows. The next morning, I pressed the power button and no POST beeps, no BIOS page, no video, no hard drive access noises, nothing. There were no hardware or software changes during this time, and no power losses or surges that I noticed. Currently the only thing that happens when the power button is pressed is the CPU fan, case fan and power supply fan all turn on, and the DVD drive spins briefly. There is power getting to the DVD drive, since I can open and close the drive tray. Holding down the power button for several seconds shuts off the PC like it normally should, but the power supply fan is now always running as long as the power cord is connected to my power strip. I have unplugged the cables and power cords connecting the motherboard to the hard drive, DVD drive, video card, RAM modules and all PCI cards. THis has not been successful in booting up either. Any ideas?

Here my system specs:
Acer Aspire T180 desktop
2.3 GHz AMD Athlon 64 X2 4400+ dual core
1 GB RAM (2 x 512MB Nanya PC2-5300 DDR2)
Hitachi Deskstar SATA HDD 320 GB
250W Delta Electronics Power Supply
FoxConn MCP61PM-AM motherboard (i think)

Thanks!

it could be your power supply, thats a very low watts there, but you said the cpu motherboard and dvd turn on, then the power supply is giving power to turn on the computer, and it worked before on that power supply.

so everything turns on except you cant get a screen on your monitor correct?

if that is so, might be your graphics card try using the vga that is in the motherboard, also take out the battery from your motherboard out for about 10-15 mins to rest the defaults for the bios.

put the battery back in the motherboard use the motherboard built in vga, and turn on your computer.

hope that helps.

How to diagnose hardware problems? I am really tempted to just say "Systematic troubleshooting" , but that wouldn't be helpful, so ...

Boot problems:
http://www.tomshardware.co.uk/foru [...] _13_0.html

You've done a pretty nice job trying to isolate the problem, and that's the essence of troubleshooting these things.

First off, I'm guessing you can't or don't really want to return the PC. You didn't build it, so is there some form of warranty?

Second, the odds are quite good that the problem is a failed power supply. Once a PC is working, the first component to go is usually the psu. Especially when its an obviously inexpensive unit. So, you might try seeing if you can swap the psu . . . to save shipping on the whole PC.

If you can't do that - or borrow a psu from someone - you might buy this:

http://www.newegg.com/Product/Prod [...] 6817703017

Its a psu that will work for you for quite a while, and worst case can be used as a backup for future troubleshooting.

Remember, it could be a different part that has failed, but the odds are its the psu.

I agree, that's my gut feeling as well.

Not a good way to buy something . . . especially from a guy named cowboom, eh?

No, mATX and ATX share the same spec for the cross-section of the psu. The only issues with psu size are the length of some of the high-powered units vs some cases. When length is an issue, its not a function of the form factor - it can occur in either type case..

Yes.

Yes. Power supplies have many failure modes. Sometimes cable(s) goes completely dead. Sometimes the psu is no longer capable of delivering clean power and/or enough power. If the damn things would just go dead, we'd all have less gray hair

Let's cross that bridge in the unlikely event we come to it.

I m having he exact same problem with my file server, no response from the screen despite all other functions working properly, PSU, USB, even tried changing RAM to other slots e.t.c and removing MB battery. Nothing.. Anyone have any other ideas.. Thanks for all the suggestions above though.

Have you tried another monitor (its obvious but its just a thought).

seeing as how you have replaced your PSU and RAM im thinking its your MoBo, also swap the video leads just so you can safely say you eliminated the possibilty.