Full HD video stutter because of CPU frequency scaling!

[zoltan87]

So I have come across a very strange issue. While I was watching a full HD .mkv video (~9 GB) in VLC media player on my T60, there were micro stutters in like every 3-4 seconds. I opened up task manager, and to my surprise the cpu usage was varying between 40-70%, and the cpu frequency was constantly changing between 1.86-1.33 ghz. So that indicated to me that my cpu should easily handle the video.

I use a program called cpugenie to run my cpu undervolted, and it also has option to enable and disable the different cpu frequency states. So I decided to lock my cpu to 2 GHz and see what will happen. I played the same video, and it was completely smooth, no stutter at all.

So my question would be, has anyone experienced something like this on his own computer? I have no idea why is the automatic cpu frequency scaling is so aggressive, that it puts it in a slower state than it's needed (or it can't rump up in time when it's required ?), I have never heard anything like this before. I want to add that this experience only happened in this one scenario so far (using vlc player), when I start a youtube video in the browser, it just jumps up to 2 ghz, and stays there for the whole video. But with vlc, the cpu frequency keeps jumping all over the place.

[TPFanatic]

I believe Intel Speedstep can be further disabled in the Thinkpad BIOS. If you're using Windows you can also lock the processor's speed to maximum with Windows power options or Lenovo Power Manager.

[zoltan87]

Yes I was pretty sure I could do that in BIOS (or even in that program I use for undervolting), but that would be pretty bad for power consumption and heat if the cpu was constantly locked to a high frequency. I wonder if there is a way to leave speedstep working, but be more careful and don't lower cpu speed in such an aggressive fashion.