Confirming The Problem:
- In Gnome, right click on the panel and add the CPU Frequency Scaling Monitor.
- When you are doing something CPU intensive like encoding video (especially after 10+ minutes
straight), notice how the CPU scales to the lowest frequency (800Mhz)
and the system feels unresponsive.
- Blow out the dust from the heat vent. This is a temporary fix. It didn't work for me.
- Upgrade to the latest BIOS. I blogged about how to do that in Linux here. And you can find the latest BIOS here.
This also didn't work for me, but the Dell has released nearly a dozen
BIOS updates this year and many of them come with performance fixes.
Might as well.
- MOST IMPORTANTLY (because this solved the problem for me) make
sure you are using a 6.7amp power supply and not the older 4.62amp power
supply that came with the older D6xxx model laptops. The supply works,
but it doesn't supply enough power to run at full speed with the fans
at full speed apparently. (So I'm guessing that it clocks the CPU and
other components down to cool the system).