Anybody have experience with smcFanControl?

Do you own an iMac?

in one, and it started to run a bit hot: one of the memory modules was around 70C, and SMART verification suggested that the boot drive was running hot as well. I grabbed smcFanController to try to control the temp. Cranking up the fans a little bit helps, according to the iStat widget: the memory module temp dropped to the 50-55C range, which is more in line with what I've seen in the past

I just don't know how safe smcFanController is

At first, I searched the threads on the Mac discussion forum. Apparently this is fairly common for many of us with iMacs. I vacuumed the vents on the top and bottom of the computer and like you downloaded the iStat program. Still my iMac occasionally ran hot and locked up. There is a diagnostic program you can run from your OSX disk to check for heat related damage if your computer doesn't have it already loaded--mine is a mid '07 computer and did not. Yesterday I took the iMac to the local Apple store for repairs. According to the aforementioned threads, it is not uncommon for heat sensors or fans to perform poorly. According to Apple, they do not recommend you use software to increase the speed of the fans rather they would prefer to check the sensors and fans and replace them so they operate within spec. Those fans have two speeds, mine never ran at the higher speed so over heating was the inevitable outcome. Hope this is somewhat helpful, if you have not searched the discussion forums on the Apple site, I highly recommend the inquiry. Many contributors had to take their iMacs in for repairs unfortunately many had to have their hard drives replaced so a time machine back up might be a prudent measure.