[mythtv-users] Stability problems with 9400GT and VDPAU

David Brieck Jr. dbrieck at gmail.com
Thu Jul 15 13:06:21 UTC 2010

On Wed, Jul 14, 2010 at 5:10 PM, Tyler T <tylernt at gmail.com> wrote:
>> I've been getting some random lockups that end with corruption of the
>> video and I'm trying to figure out what to do about it.
>> What I didn't know before purchasing was that this particular card
>> claims to need at least a 300 watt PS. Is that normal of these types
>> of cards?
> I'm afraid they are rather power hungry. I had to upgrade my 60w PS to
> 80w just to add a little PCI 8400 GS card. That thing is specced at
> 71w TDP which is probably way more than the PCI bus is designed to
> handle! Fortunately, it only seems to need that much juice with heavy
> 3D action. I haven't been able to test mine yet to know if my 80w PS
> will handle my 32w CPU + VDPAU, but I'm keeping my fingers crossed
> (and plan to underclock).
>> I'm thinking it could either be heat
> You should be able to run the nvidia-settings utility to view GPU
> temperature. Make Myth non-fullscreen so you can watch the temp as a
> recording plays, to verify.
>> or lack of power that's
>> causing my problems, but power is something I have a limited supply
>> of.
> Look up the TDP of your particular video card (they vary). (I realize
> TDP does not equal current draw, but it's prolly close enough.) Add to
> that not only your CPU wattage, but also your hard drive, DVD drive,
> etc as well as some fudge factor for DC-DC/VRM losses, fans, etc. Or,
> go buy a Kill-A-Watt or similar ammeter and see what happens (remember
> a 275w PS at full load will draw probably over 300w at the wall due to
> power factor and other inefficiencies).
>> The case has a non-standard PS that can't be upgraded easliy so of
>> course I'm hoping it's not power.
> This is part of the reason I chose a case with an external brick-style
> PS. I realize that doesn't help you in the slightest, especially since
> it's hard to find bricks rated for more than 120W or so, but I mention
> it for the benefit of others to consider uATX or other standardized
> solutions over proprietary. Say, one thought does occur to me -- maybe
> a PS designed for a 1U rackmount server would fit in your case. It's a
> long shot, though.
>> If I underclock the GPU, how low can I go before I can't use VDPAU to
>> play HDPVR recordings?
> We're discussing this a little bit in the nearby "Nvidia underclocking
> vdpau" thread. Apparently, nobody seems to know yet, so please try and
> let us know what you find. :)

Thanks for your responses.

Last night I went into the BIOS and shutdown one of my two cores in
the hopes of saving some power. I also put the CPU into powersave mode
using the little power control applet in Gnome. I couldn't figure out
how to underclock the GPU though, but I did find the TDP and it's
rated at 50 watts. So that combined with my CPU at 65 watts leaves a
little leftover for the hard drive and motherboard. I disconnected the
DVD drive and plan on pulling it out to put in a fan, just in case
it's heat causing my problems.

I was also considering pulling the hard drive out and replacing it
with a little flash drive to save even more power, but I don't know if
those devices are even on the same rail.

If all of this doesn't work I think I'm going to try a normal ATX PS
external to the case to see if that solves my problems. If I can find
one with long enough cords it should be able to hide behind my wall
mounted TV.

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