Power Supply Question

I have an "old" socket 939 system and the moterboard died on me, so I tracked down a new motherboard (a Tyan Tomcat S2866A2NRF-RS) for a decent price in order to save it.

The thing is the Tyan calls for an EPS12V PSU and all I had was an ATX12V, and no intention on buying a new PSU. Not knowing quite what to do, and not having a working system to get online and ask here , I plugged the PSU's 4-pin into one side of the MB's 8-pin socket, and noticed there was also a molex socket on the MB, so I populated that as well, hoping that it was intended to take the place of the other (empty) side of the 8-pin.

Surprisingly, to me anyway, this worked out and everything seems to be running just fine. But I am worried voltages could be off and components could be damaged.

So, is this set up OK the way I have it now, or am I jus asking for trouble? Your expertise is much appreciated