Event Viewer revealed the following events in succession for each core of my laptop's quad core Intel i5 CPU:
The speed of processor 0 in group 0 is being limited by system firmware. The processor has been in this reduced performance state for 5 seconds since the last report.
Windows slowed down to the extent that I couldn't even open Task Manager, which normally comes up readily even if the system is otherwise sluggish. Interestingly, in this state it would enter Sleep Mode eventually upon closing the lid, but was otherwise unusable.
Several steps can avoid these slowdowns:
- In your system BIOS, disable Intel SpeedStep.
- In Windows 7, ensure your system uses the High Performance setting for Power Plan.
- Ensure adequate cooling with a utility like SpeedFan to monitor temperatures.
However, based on at least one thread in the Dell support forum and another on a hardware forum, this could turn out to be an indication of a hardware problem.
Intel SpeedStep is triggered to activate, among other things, by heat. If the system is heating up and can't dissipate heat effectively, SpeedStep by default will engage and step down the CPU so that it generates less heat. Whether that heat is generated by the CPU itself as a result of a dead heatsink fan or the heatsink somehow being detached from the CPU surface, or the GPU overheating for whatever reason, or heat simply can't dissipate due to factors like lack of ventilation thanks to dust or covered vents, it will try to compensate by throttling down the CPU speed.
While this seems perfectly reasonable in theory, in practice it seems to not work as intended, at least in the case of my E6410. I've read reports in the very helpful Dell Latitude E6410 Owner's Thread that some have had similar issues which necessitated a mainboard replacement, while others were able to get up and running by just clearing dust out from the vents of their laptop.
My particular situation, however, doesn't seem that common, which makes me wonder whether my GPU might be on its way out. Yesterday with the laptop on battery and without a lot of ambient noise, I noticed that when I would ALT-TAB from say a mostly white background to a vividly colorful one, a distinct whine would be emitted from my system, and the display wavered just slightly as if some interference were rippling across the video hardware (update on this, according to some info in this thread, this whine is characteristic of systems with Intel Core 2 Duo and newer CPUs).
For now, I've disabled SpeedStep and installed SpeedFan to keep an eye on temperatures, and cleaned out dust. Hopefully this will do the trick, but if not, given this and the sound problems which continue to plague my E6410, a warranty comes in handy. I added a link to my bookmark toolbar to the aforementioned E6410 owner's thread, it seems Firefox sympathizes with my plight based on how it shortened the bookmark title. Ow indeed, Dell!