HP Pavilion 7920 Power Supply to Motherboard connection Help

I was given a few computers that had been torn down for parts, but never really parted out (I received most of the parts). I was able to resurect 2 of the 3 minus the hard drives.

One is a HP Pavilion 7920. The power supply had been removed from the case. That is where my question comes in. There is one connection off the power supply that I haven't seen before. It is similar to a floppy connector design style, but it is a little smaller. It only has 3 wires (1 green and 2 black). There is a connection on the motherboard that fits this connector. The motherboard states PS_FAN at this connection. Someone mentioned this could be a lead to monitor the PS fan (but they also mentioned different colors for the wires). I'm wondering if the lead out of the ps should be hooked to this connection?

Here is a snapshot of the motherboard (scroll down).

http://h10025.www1.hp.com/ewfrf/wc/genericDocument?cc=us&docname=bph07170&lc=en&jumpid=reg_R1002_USEN

The MB connector I am referring to is #21 on this page.

I contacted HP via email and they were of absolutely no help - they routed me to a generic PC building site, and then general instruction on a power supply replacement - nothing specific to the 3 pronged wire and receptor, which is where my question lies.

I thought the lead out of the p/s had something written on it, but I don't have it in front of me at the minute. I'll try to post an update tonight.

Any help appreciated!!