Very Odd Problem - Please Help

[Laudanum]

I have gone to various message boards, scoured thru search engines, and brainstormed to no avail.
My problem is the following:
I (foolishly) took on the task of helping my brother fix his computer. He doesnt have alot of money and I am decent with computers so I figured it would turn out fine. He has a Pentium III 1.0Ghz Compaq computer. The problem is that when you turn the computer on - the keyboard/mouse/monitor dont turn on. Once in a while they will - but you have to keep shutting the computer off and turning it on until they (randomly) come on. The monitor is known to be good.

I have installed a new video card (to replace the onboard video). I replaced the crappy power supply with a nice unit. I have swapped in new hard drives. Which leads me to the assumption that it is either the motherboard or the memory [not much left in this pile of crap]. But I dont really know. Does anyone know why this occurs?

Thank you very much in advance
L

 

[Anubis]

first id check them mem. it could very well be that as you suggested. if it isnt then either the Mobo has died or teh CPU died. and thats really crappy 🙁

 

[Laudanum]

Why would it sometimes work and sometimes not? Could that be the CPU? Everytime I push the button the computer led light comes on - would this mean anything? Or just that the PSU is working?
Also - how can I be assured that this system has a MicroATX board...to my eye it doesnt look like a full ATX?
Thanks alot
L

 

[wyvrn]

I would bet it's the motherboard since you already tried a new power supply. I doubt the memory would cause the keyboard and mouse to malfunction, but I guess it's possible. Check with Compaq to see if it's still under warranty.

 

[Laudanum]

No its not under warranty. It started this nonsense right after the warranty ended (as things always do).

 

[LouPoir]

Sounds like a motherboard problem.