Dell e6400 and e6500 users: you may be a victim of Throttlegate!

Apparently, these Dell E6400 & D6500 laptops come with some aggressive CPU throttling problems.  If you google for "Throttlegate", you get links to stories about our laptops slowing themselves to as low as 100Mhz for various reasons usually related to overheating.  I was hit by it, and I wanted to share with you how I fixed the problem.

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.
Solving The Problem:
  • 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). 
If you are using one of the newer Dell E6X00 models, make sure your power adapter is glowing blue where it plugs into your laptop.  If it doesn't glow, you probably have the 4.62amp power supply and your machine is probably running REALLY SLOW when you most need for it to scale to full speed.

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