there are little tabs on the metal contact parts (pins) that you can push in. I usually do this with a straight pin but that's just me. Factory spec fans will plug into the 12v + and ground wires, what antec has done is incorporate a temperature dependent resistor (thermistor) into the PSU that increases the fan's voltage as temperatures increase. Simply removing the unused wires will not cause your fans to spin slower/be quieter. If you really want to mod your PSU to run your fans quieter, you could cut off the gnd wires at the psu, cap the stubs with insulation (electrical tape, heatshrink), remove the extra wires from the connectors, and rewire a string to be for 7v fans. This would make your fans run slower and be quieter, but this setup will not have any temperature sensors or anything like that. Many people (myself included) will usually just rewire a 4 pin type fan such that the fan and all "regular type of wiring" fans after that fan run at 7 volts. There's many posts here and at other places about the "7 volt mod".