SFF Optiplex 745 runs hot

I have a few Optiplex 745 small form factors here, and one of them had the hard drive fail on Friday.  I noticed that the drive was very hot to the touch when I was troubleshooting the problem, and I suspect the heat may have led to the drive failing.  I installed SpeedFan on another 745 and found that the hard drive temperature hovers around 51 degrees Celsius which seems pretty hot.

We also have some Optiplex GX260s around here, and it seems like they run a lot cooler.  Their fans tend to run at high-speed more frequently as well, which seems to help.

On the other hand, the fans on the 745 rarely (if ever) seem to run at the high speed.  Is there any way to adjust the settings so that the fans kick into high-speed mode more frequently in order to maintain a lower internal temperature? SpeedFan doesn't seem to read the fan sensors, so that doesn't work.  I've checked the BIOS settings and can't find anything related to this.  Are there advanced/hidden BIOS settings?