power supply compatibility issues

[bluejay]

hello I have a asrock P4i465g mobo with a intel 3.00 processor. Until recently I had a atx450 power supply that was functioning ok but I wanted more juice to run a AGP card. I decided on the corsair gs600 and when I changed it out my system wouldn't boot up. Taking it back to the store the clerk tested it and suggested i try it again. Now after close examination i see that the the corsair is missing a lead on pin 18 & the other power supply is not. My question is does this motherboard need the 5 volts on pin 18?
thanks