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

[sonofzev at iinet.net.au]

I hate to throw a spanner in the works.. but my experience has differed...I
happily run my socket 939 Opteron chips at 1000MHz with no adverse impact on the
image (running VDPAU).. The only differences I have noticed have been related to
the video card in use.  

>Many thanks to everyone who has responded. I'm learning a lot reading
>your posts, like getting a video card might not have helped and a 
>different CPU would help.

I have an Opteron 146 (socket 939), I have the governor set to ondemand and am
allowing it to go to it's lowest speed of 1000MHz 

I have used both an 8400GS with 512MB of onboard RAM and an 8600GS Silent with
512 MB RAM and an 8600GS with 256MB. The monitor is a 1600 x 1080 resolution.. 

I also have a very similar system but with an Opteron 170 (socket 939)...The
setup is almost identical but it has an 8600GS silent with 256 MB of RAM and goes
to a 720p LCD TV. Both systems have 2GB of dual channel DDR 400 Ram.    The
motherboards are both fairly high end for their time, one has an ATI chipset the
other is an nforce4 chipset.. but that doesn't change the fact that the memory
controller is on chip.. 

I have not had any problems with the CPU being throttled to 1000MHZ.. The only
problem I had was when trying to run anything higher than BOB 2X on vdpau with
the 8400GS... with the 8600GS I can run Advanced 2* with 1080i content without
any glitching, tearing or anything visual problems on both of the systems.. 
So I have only noticed a difference in performance based on the video card.. 

The only thing I can think that might make a difference is that the Opteron's
have double the L2 cache.. 
   




On Sun Oct 24 12:55 , faginbagin  sent:

>Many thanks to everyone who has responded. I'm learning a lot reading
>your posts, like getting a video card might not have helped and a 
>different CPU would help. But I'd like to work with the hardware I've 
>got, so I think my solution will involve getting the CPU frequency right.
>
>Let me make sure I understand correctly. It should be possible to take
>advantage of Cool n Quiet. It should just be a matter of tuning the 
>ondemand governor to get the PVR-150 and 8300 IGP to function properly. 
>It should be sufficient to add:
>
>echo 1800000 > /sys/devices/system/cpu/cpu0/cpufreq/scaling_min_freq
>
>to /etc/rc.local, right?
>
>What are the chances this would also allow use of the VDPAU Normal
>profile with 1080i content and closed captions? Perhaps it's up to me to 
>experiment?
>
>FWIW, before I opened this can of worms by tweaking the BIOS and when
>the computer was mine with two HVR-1600s and a 8400GS, it was drawing
>about 60 watts at idle. I think it would be useful to see what the power
>draw is now with Cool n Quiet, different tuners and no video card.
>
>One thing I noticed is there isn't much difference in fan speeds
>with the performance vs ondemand governors when the system is idle. The 
>CPU fan runs maybe 100 rpm faster with the performance governor (high 
>1600s vs high 1500s with ondemand). And the chassis fan seems to be 
>about the same, a little over 800 rpm. Temps for CPU cores are 27 to 33C 
>and MB temp is 35C (don't know about ondemand). Seems reasonable to me 
>and which is why I'm wondering if it's worth the effort to do any fine 
>tuning. It certainly would be easier to disable Cool n Quiet in the BIOS 
>and be done with it. But before I take the easy route, I will compare 
>power draw at the max (2.5GHz for the 4850e) and 1.8GHz frequencies. If 
>there's a difference, I'll take the time to do some fine tuning.
>
>Thanks,
>Helen
>
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