Perry,
Given the 100°C spec referenced in CoreTemp FAQ, I've been content to let the system hammer away at 80-90°C. It's been running all 8 cores that way consistently since my last post, and I have had no issues. I'm trusting that Dell can manage its own CPU cooling requirements. At this moment, with 72°F ambient, core temps are 71-86°C - safely below 100°C. The fans are slightly louder than when the CPU is at idle, and I like quiet these days.
I have an option for you that may work if your system is like mine. As I mentioned in my original post, the chassis intrusion switch appears to disable the normal fan control and runs them at full speed. You might be able to disable it permanently by unplugging from the motherboard or rigging the switch so it shows intrusion, though you may get an annoying boot notification every time you restart.
When the fan controls were disabled, I found that I could use SpeedFan to regulate the speed of the fans. Note that SpeedFan is very powerful, but also somewhat complex, and it seems inconsistent in what fans it can control. You can also setup component temperature criteria by which SpeedFan will alter fan speeds for you. NOTE: You could easily set things in such a way that could cook your CPU. I recommend you install SpeedFan before you disable the chassis intrusion switch. It will report the fan speeds to you, so you will have a baseline
Good luck!
Steve