After re-assembly, iMac 27" fans blowing at full speed all the time After disassembly and reassembly to fix an HDD cable issue, my iMac is now a blowhard - the fans are going at full tilt from about 30 seconds after boot. I don't believe the device is overheating - I surely messed up one of the temperature sensors upon reassembly.

My question - beyond carefully checking each JST connection and making sure I've re-attached all the sensor cables on the motherboard, is there any way I can control the fans via software? I believe I have more-or-less permanently damaged the skin sensor - so can I disable that through software configuration or a 3rd party utility?

UPDATE

It's not the HDD / SDD temp sensor, by the way, since it's not the HDD fan that's spinning that hot, but it certainly is one of the other sensors. The ODD fan's RPMs are strangely high, but it's the CPU fan that's out of control. Mac's Fan Control is definitely doing the job for now (I'm using the CPU heatsink temp as my RPM controller). I'll need to get in there and determine which of the sensors is the one acting up.

I wonder whether I can tell which sensor is acting up based on either A) the list of sensors appearing in the Mac's Fan Control sensor list (or, more precisely, the sensor that's NOT appearing in that list) or B) the temperature of a given sensor that's way out of whack.
Yes, there is a 3rd party app called Mac's Fan Control which allows you to adjust the speed of your fans. It gives you the current speed of your fans and has different options for setting the speed. You can set a variable speed which forces the fans to go faster as temperature goes up - as they are supposed to do. 

there is also an app Temperature Gauge 4.1 that lets you monitor the temperature of different areas of your Mac and the fan speeds.