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If I remember correctly, SMC Fan control software (
http://www.macupdate.com/app/mac/23049/smcfancontrol ) will force the fans to run faster than minimum RPMs set by its hardware controls. This software cannot force the fans to run slower (slower then Apple Defaults). To eliminate H/W controls, short out the HDD TEMP pins. I too see this trick (fix) as a common theme when upgrading to SSDs.... Program called HDD Fan Control works. re:
http://www.hddfancontrol.com/ (without shorting out the wire).
To short out the temp sensor, simply leave the little wire connected to the mother board pins, cut the wire approx 3/8" away from its connector, strip its plastic - to expose its bare wires, twist its wires together, paint some finger nail paint on the bar wires (or liquid electrical tape - which is much better), then reassemble the iMac chassis. This works for me...