help DIANOSING dead sys after HSF changeout

SYSTEM SPECS:P5N32-E SLI, e4300, 2x1gig Crucial Ballistic Tracers 800mhz, 8800gts-320, PSU Antec TPQ 850, Antec 900 cable modded, XP pro 32 sp2

So last night (because I was bored) I decided to change out my HSF to an Artic Cooler Freezer 7 Pro.

There was a big Zalman on there (don't remember model) that's meant more for silent cooling instead of overclocking potential. Example: e4300 at 2.25GHz (stock 1.8), 1.25v, was hitting 60Celcius (via Everest and Core Temp) at load (via Orthos two instances).

I put the mobo back in the case last night. Tedious with the Antec 900's limited space.

This morning I put the vid card back in and tried to fire it up.. that's when the cussing started.

PECULIAR BEHAVIOUR:

When I turn on the system it fires up (all fans, including HSF).
Then it shuts down after about 2 seconds.

If I turn it on again it fires up and stays on, but I get nothing on the monitor (except check connection) and I'm not noticing any hard drive activity. (I'll have to confirm HD activity when I get home.. at work right now)

NOTE: this process repeated several times... I'd walk away for awhile... come back and turn it on only to have it shut down after a second and then turn it on again and it would stay on

THINGS I'VE TRIED:

- cleared CMOS on mobo
- checked all connections
- reseated the video card
- tried alternate output on vid card

THINGS I MIGHT HAVE DONE WRONG

- I left the cpu in the socket and cleaned it with rubbing alcohol to get the old compound off. I've done this before with out problems, but unsure if it could be harmfull.

- Pulling and Replacing the mobo is precarious in that case. Maybe I harmed it.

- Maybe I messed up mobo when I put the HSF on. Takes considerable force.

- I'm going to check the 24 pin power when I get home.... it's a 20+4 connector and I'm wondering if I could have reversed the 4 (?)

Thanks in advance to all who throw out some ideas for me.

If I can't get it to work tonight I'm going to have to do a complete tear down and start testing parts... I really don't want to have to do that. Cables are all carefully routed etc.

aux 4 pin connected... yeah I forgot the 20+4 is rounded on one end so that's not it... power connections seem good, cmos cleared