[mythtv-users] CPU performance governor vs disabling AMD Cool n Quiet

[dlknight at sdf.lonestar.org]

> Hi Mike,
>
> Yes, I have updated the BIOS and I've got 512MB dedicated to the IGP.
> Perhaps the reason why it's working well for you is because you've got
> an Athlon II, which, as Kevin mentioned, doesn't reduce bus speed with
> CPU speed.
>
> An update: I took my kill-a-watt over to my sister's and found the power
> draw at idle was pretty much the same no matter what the CPU frequency
> was set to, within 2 watts. And it seemed to me that playback of 1080i
> content was smoothest at the max CPU frequency. So I took the easy route
> and just disabled Cool n Quiet in the BIOS. That way, I've got fewer
> things to remember to configure when the time comes to install a newer
> OS/distro.
>
> FWIW, at max CPU frequency, VDPAU Normal with closed captions wasn't
> smooth. So, back to VDPAU slim. She's happy with the playback quality,
> so I probably won't get her a video card in the foreseeable future.
>
> Again, many thanks for everyone's help,
> Helen
>
>
>

I have the same motherboard but I'm now using a 9400GT for VDPAU duties, I
found that the minimum clockspeed when using the ondemand governor was too
low and when watching video it wasn't raised because the CPU wasn't loaded
- most people agree that the low clockrate causes the bus speed to drop as
well hence the video chip not receiving data quickly enough and
stuttering. This may also be the problem affecting the capture cards as
they will also require the bus speed to be higher.

See section "CPU Frequency Scaling" on the mythtv VDPAU wiki -
http://www.mythtv.org/wiki/VDPAU

I found that a minimum frequency of 1800MHz was required for trouble free
video playback.

I found that with this tweak I could enable Temporal 1x/2x for VDPAU but
could not get the silky smooth Advanced 1x/2x to play stutter free hence
upgrading to a 9400GT.

Regards

Dave K.