S5375 not booting, is it this power supply?

Hi all,

I was building up another number cruncher using an S5375 (i5100x) with 2x E5420s (2.5GHz Xeons) and since there was a Zalman ZM-500HP lying around and the specs on the sheet read ATX12V, 24+8 pin connectors I decided to wire that up. Sadly the thing doesn't boot at all, no video or beep (unless I take all the RAM out!) so was wondering if anybody knew if this was totally incompatible. It's only a 500W power supply, but it's on internal graphics and only a couple drives, plus this power supply can push 600W if needs be. It makes up the EPS12V with two 4-pin connectors, so it can fit standard ATX12V as well.

Board specs: http://www.tyan.com/product_board_spec.aspx?pid=566
PSU specs: http://www.zalman.co.kr/ENG/produc [...] sp?idx=195

I did take out all the peripherals and even hard drives but still no joy, which made me finger the PSU. I guess if that's not it either the board or the chips are bad, which would be rather a downer.

Cheers,
rdgh