Computer won't power up..Fan runs like it's going to

[xxXplicitP]

I am having this SAME exact problem. I have tried switching out different Power Supplies/Video Cards/Cords/DVI, VGA Plugs except changing the Motherboard. So I am going to conclude it is my mother board.

[Karnac]

If the capacitors are leaking or crusted (they have a + on top of them) then the motherboard is usually toast......I continued to use a motherboard with 9 festering caps for over a year until the keyboard port failed and an acrid odor started.

[Aegis]

an acrid odor started

Nothing like the odor of failed electrical components.  I experienced it last year with a "blown" power supply.   

[TheHoFL]

We see this all the time at work with older machines. Most of the time the CPU is still in working condition, but the motherboard definitely needs to be replaced. I find that the computers here with blown capacitors usually are due to a heat problem cause by dust buildup. I have also had that happen with projectors.

Most recently my personal laptop had the same issue 

[baldelocks]

Its funny you say that. When I opened mine up the heatsink was full of dust.

[TheHoFL]

LOL ... could have assisted in disabling your computer. 

[baldelocks]

It just gives me the opportunity to learn something new!!

[TheHoFL]

That is an excellent way of looking at it.  I'm glad you think that way!