Computer won't start (advanced issues)

I could bore you to tears with every detail so I'll try to be as concise as possible:

ABIT AS8 MOBO (then INTEL MOBO)
4 GB DDR RAM
ANTEC Sonata Case, w/ 380 watt PSU (Then 2 other PSU's)
P4 CPU, 775 Socket (2 Different ones)
Regular stuff every where else: soundcard, video, LAN/NIC card, etcetera

Nothing too exotic here. One day it began it's slow demise. Turning off, then on. Partial boots. Then down to nothing, which is the fans (CPU, PSU and case) spin for about 3 or 4 seconds then right off. Here's where the fun begins...

1. Replaced power supply 3X: Same thing.
2. Did the pull each card, each stick of ram, each HDD, all peripherals and attempted to start after each pull: NO GO.
3. Bought another CPU fan: No go.
4. Bypassed power switch: No go.
5. Got another MOBO: Same thing as before using all aforementioned stuff.
6. Got another CPU: Same things, all things.
7. Was told to try MOBO outside of case--Nothing there too.
8. ????

In fact I've tried mixing and matching stuff. Different cords. Different wall outlets. I mean I've got two PSU's, 2 MOBOS, 2 CPUS. And I keep getting the same 3 to 4 seconds of fan spin and off.

Here's what I'll try next:

1. Jumpers on the CMOS.
2. Another case?

Could I possibly be frying stuff and not knowing it? I'm using a leftover DELL plugged into the same outlets and it isn't having any of these issues right now. Grounding issue with the case? Bad power or reset switch in that Antec case? Will I need some peripherals plugged in to get somewhere? Like the HDD's or video card? Does both the power and reset switch need to be hooked up for things to work?

I'm just out of ideas and don't know where I could have gone wrong. Sooooo, any help is much appreciated.

Sincerely,

Frustrated

At this point I can only say, with the Intel MOBO, that I'm getting 3 beeps with NO memory installed. If I put a stick in I get nothing. Again just 3 or 4 seconds of fan spin and then everything stops.

The ABIT doesn't beep at all and it's LED code is 9.F or 9.9, which I read doesn't tell you much of anything.

I posted to another forum and was told, perhaps, I may have screwed myself buying used...Student on a budget situation here.

First I would recommend clearing the cmos. The easiest way is probably to pull the battery.

Ok, try booting with 1 stick of RAM, cpu, HD, and video card with the board outside the case. It's better if these are non-dell/factory parts.

It's very unlikely the case is causing the problem. About the only thing that can go wrong on the case is the front panel switch. But it sounds like your system is getting power, so the switch works. Maybe double check that the power wire is on the pwr connector (not the reset).

Unplug everything else, this will give a good starting point.

Thanks for the update. Hopefully it all work as normal now. Let us know how it works out for you.