Uhh..? Computer problem =/

[Raion]

My desktop computer is about 8 years old, 567 Mhz 192MB RAM running Windows XP (although the specs are irrelevant to the problem). About 2 weeks a go, I left my desktop to idle as I used my laptop right next to it (a great waste of electricity..but I wanted to use AIM while FEAR loaded ) and suddenly..it shut down.

Naturally, I went to power it back up thinking it might've over-heated and shut down since the fans are pretty old but I've changed the processor fan once and the fan on front seems to be really good since it's still working. However, it didnt boot up, so I switch into troubleshooting mode and first I check whether the surge was overloaded, the reset switch wasnt out so I move on and connect the cord to another part of my surge, that didn't work so I connected it directly to two different wall plugs, that didn't work.

I opened up the computer and noticed that the light on my MoBo that indicated that it is receiving electrical current wasn't on. My conclusion, as many others would've probably been, was that the PSU was gone (for the second time in 8 years) so I bought a 450 Watt PSU that supports SATA and says ATX Switching Power supply (I have a mini-ATX mobo..idk if that will be a problem although I doubt it).

I had the PSU tested at the store because I couldn't return it because it's an electrical component (bleh..). The test was only supported when I connected the PSU to the wall at home and the cooling fan in the PSU did a single spin showing that it is receiving current. But still, the MoBo light wasn't powering on and turning it on obviously didn't work.

At this point I'm tempted to say that it is the MoBo but I don't want to buy such an expensive piece and find out that that's not the problem either (that and money is an issue at the moment since I need to get this problem resolved before I leave to college again). So my simple questions are:

A.) Is there anyway to test whether or not the motherboard is working without any extra tools or extra computers.

B.) If not the motherboard or PSU what else could it possibly be? I'm stumped.



P.S. Sorry for the long post Wanted to provide as many details as possible to get the most accurate replies.

UPDATE: In a bad mood, I decided to pre-occupy my mind with attempting to fix the computer again. I decided to unplug all the other power cords besides the main connector (HD, DVD-RW Drive, Fans) and connect that in hopes that for some odd reason that would work. I also decided to connect it to an extension cord I had since I was too lazy to free up my surge protector.

When I connect it, immediately the PSU fan turns on as before except this time it doesnt stop. Then I look down and see the MoBo light turn on but just as fast, it turned right back off and the PSU shuts off. :-/ I try again to connect my PSU and turn it on and off and now the PSU fan doesn't even attempt to spin. I switch out the cord with 2 others I had laying around and that wasn't it either. As I'm typing this I've come up with two new possible problems:

A.) Loose soldering somewhere? Or broken MoBo (Although I saw no visible broken pieces upon quick visual inspection under heavy light)

B.) This isn't a problem but an explanation as to why the fan on the PSU might've turned on earlier re-enforcing point A: possibly the PSU fan turned because it was sending current to the MoBo briefly and the light didn't turn on because it does have a one second delay.

Help is greatly appreciated