Enermax460W PSU question

I have the above PSU and one of the leads terminating in a Molex connector is labelled "Extra". I can find no mention of this in the manual, but it does mention a +5VSB at 2.2A.
At the moment I am using this connector to power my vid card (9700 Pro)with no problems but was wondering if it is likely to cause a problem?
If it is something to do with the +5VSB it was my understanding that this supplies power even when the PC is switched off.

Not to my knowledge... and wouldn't expect it to affect your performance/stability of the card/system.