x1700 MB won't boot up with new psu

I bought an Acer Aspire x1700 a while ago, but I've been meaning to put in this geforce 7900 gs I have. I bought:
-Thermaltake V3 case (http://www.newegg.com/Product/Product.aspx?Item=N82E16811133094)
-Corsair 500W psu (http://www.newegg.com/Product/Product.aspx?Item=N82E16817139018)

Last night I moved the x1700 mobo (with stock cpu fan and ram) to over to the Thermaltake case and new psu. With the main power connector (20pin piece) plugged in, 4 pin connector, and front panel power switch line connected to the mobo, the cpu fan spins up for 1second and stops (no boot).

At first I thought it was shorting out on the case and put pieces of paper between the board and standoffs, but that didn't make any difference. I left the board in the new case and connected the old psu (held it by hand) and it booted into BIOS fine. I also did the paperclip functionality test for the psu--with a 120mm fan connected (http://www.corsair.com/cinema/movie.aspx?id=1358543), but I don't know if that rules out other kind of psu failure?

Could it be the motherboard is somehow locked to its 220W proprietary psu? Could it be something wrong with the PSU? or is the psu somehow incompatible with this motherboard? (it shouldn't be?)
Does anyone know or have any ideas why my motherboard won't boot when I connect it with this new psu?
I am tempted to pull out the power connectors from my other working build to see if it will boot up the motherboard, but I would like to hear your opinions before going through the trouble to pulling apart that computer!

Motherboard: http://www.ascendtech.us/itemdesc.asp?ic=MB4ACMBSB801002
Motherboard info: http://support.acer.com/acerpanam/manuals/acer/0000/servicemanuals/SG_ASX1700_VTX270_Book_1031.pdf (p67?)
Corsair psu specs: http://webcache.googleusercontent.c...ors&cd=1&hl=en&ct=clnk&gl=us&client=firefox-a

Nearly every time I see an issue with the fans spinning for a second then nothing; its a bad power supply. YMMV.

OMG I figured it out! I pulled the 20/24 and 4/8pin connectors out from my other build and hooked it up to the Acer motherboard, and it started just fine.
Then I realized I still had the optical drive and case fans connected to the PSU, so I tried to the new Corsair again but instead of only plugging in the 20pin and 4pin, I hooked up the optical and graphics too and it booted just fine.

So the computer is working fine now

For some reason the PSU wouldn't run with only the 20pin and 4pin (I thought it could?). Maybe the motherboard by itself wasn't drawing enough power??
Anyway, it's working for now. If this isn't something the PSU is supposed to do and is a sign that it's faulty, please let me know!!
Thank you for the reply!

New one on me. Congratulations.

Welcome to the forums and merry Christmas.