Friday, May 29, 2009

The Acpi 2.0 _PCT object returned an invalid value of 7

So, I've been fighting a stuttering issue with my laptop, an Alienware Aurora m9700, for the last few months now. Whenever I played a movie file it would start stuttering badly after about 20 seconds, and then every 10-20 seconds for 2-3 seconds. In .mov files, this affects the sound, but in all others, it affects only the video. The same held true for games. I was unable to play any games (on a gaming laptop!) due to the crippling drop in FPS every 10-20 seconds.

I tried reinstalling the OS a few times. I tried updating this driver or that. I fiddled with BIOS settings. I fiddled with video card settings. I spent hours researching it online using variations on the terms "stuttering video xp seconds fps chop 'frame rate'" and a host of others.

Two nights ago I was looking through the Event Log on a whim on a completely unrelated topic, having all but given up on the stuttering issue. At that point, I was all but convinced it was an SP3 issue, and there was nothing I could do about it.

But I came across this: "The Acpi 2.0 _PCT object returned an invalid value of 7". Hmm… Acpi… power management… and my fan has been going mad the last few months. More than I remember it going when I first got the laptop. Still could be SP3… I've heard it jacks with power management. But I keep looking through the error log, and this error seems to coincide with the stuttering incidents.

A google search for the error string, and I come across a lot of things related to (get this) stuttering during video playback and gaming.

From looking around, it could be one of the following:
  • Broken heat pipe
  • Unseated CPU heat sink requiring the reapplication of Arctic Silver (or similar heat sink paste)
  • Dust on the heat sink and/or vents
  • Faulty CPU
  • Faulty motherboard controller
  • Faulty drivers
Huh. Some of those are pretty expensive. So I think about it, and decide to start with the easiest. Grabbing a screwdriver, and air canister and a flat surface, I take the bottom panel off the laptop, revealing the cooling pipes, heat sinks, and other various whatnots. I do this 1. to inspect things b/c I still love the look of computer circuit boards, and 2. to give the dust a place to go after I hit it with air. I do so, and nearly blind myself with the dust that saturated the air in my kitchen.


Coughing and hacking, I put the panel back on, boot her back up again, and notice immediately that the fan is a LOT quieter. It's odd, actually, I could actually barely hear the HD clicking. That had been drowned out by an overworked fan just minutes before. I head over to and load it up. It used to say "Your CPU may be too slow to process HD video, would you like to view the low res version?" right about the time it would start stuttering. Even the "low res" version would say that same thing.

I watched, my anticipation mounting, expecting the video to stop and stutter any second… or at least expecting the fan to kick in loudly… neither happened!

Months of frustration and trouble, and all b/c the heat sink and vents were full of dust.

I wonder how much longer I could have gone before I actually damaged something.