This is how I made my 600cs quiet, first I changed the 120mm fan out with a ANTEC 120mm fan with built in temp control. Second was to change the stock CPU fan to a Thermaltake spark 7. The new plastic bracket that comes with the spark 7 and attaches to the motherboard only needs the plastic clips that would hold it into a regular motherboard pressed out once that is done the holes will look exactly like the stock hole allowing you to use the stock screws to hold it in place. I then used the pigtails that came with the fans to connect the fans directly to power supply and cut the connectors off the stock fans and spliced the white wire to the tach wire off the new fans. Use of the temp sensor or manual control for the spark 7 is upto you. I just used the temp sensor so it can adjust itself. Now the loudest thing in my 600sc is the whine of the harddrives.