[mythtv-users] Which NVidia card

[Steve Smith]

On 21/01/2008, Marius Schrecker <marius at schrecker.org> wrote:
>
> > On 21/01/2008, Cal <cal at graggrag.com> wrote:
> >>
> >> Marius Schrecker wrote:
> >> > Hi,
> >> >
> >> >    After a Loooong break I'm trying to breathe new life into my
> MythTV
> >> box.
> >> >
> >> > Why didn't I listen to you all before when you warned bout ATI cards?
> >> I'd
> >> > have saved myself a lot of grief! Anyway:
> >> >
> >> > Now I'm going to get a card that does proper XvMc (Nvidia the only
> >> choice
> >> > here??)
> >> >
> >> > The box will only be used for MythTV, so great 3d performance is not
> >> an
> >> > issue.
> >> >
> >> > Card should be PCIe, available (7000 series or 6200TC), passive, and
> >> not
> >> > generate too much heat. I'va lso read mixed reports on whether the
> >> 7000
> >> > series DOES support full XvMc, so questions are:
> >> >
> >> > 1. Is it correct that the 7000 series does XvMc without problems?
> >> > 2. I can still get hold of a 6200TC, but this has only 64 MB Ram. Is
> >> this
> >> > sufficient?
> >> > 3. Will the 7300 GS produce much more heat than a 6200TC? Could I
> >> > underclock to compensate?
> >> >
> >> >
> >> > 4. Other recommendations????
> >>
> >> Forget about XvMC. It's a relic of a past era where our poor struggling
> >> sub-2G single core cpus _needed_ some graphics processing to be
> >> offloaded
> >> in
> >> order to survive. So, the poor little graphics card endured constantly
> >> cooking up a storm doing XvMC, and without even a fan to cool its brow.
> >> Now, I believe you're better off letting a nice little dual core do the
> >> hard work. It's better equipped to deal with the heat output too.
> >>
> >> Worst of all, XvMC comes with some tedious artifacts. You don't get
> >> anything
> >> for free. My suggestion is have the graphics card do no more than it
> has
> >> to,
> >> and provide the necessary grunt via cpu instead. I have a 6200 and a
> >> 7300
> >> (two systems), and I really can't pick between them. They're both
> >> excellent as
> >> long as I don't try to include XvMC in the mix.
> >>
> >> Cheers.
> >>
> >> (I could really use a "Loooong break", can you recommend a good
> source?)
> >> _______________________________________________
> >> mythtv-users mailing list
> >> mythtv-users at mythtv.org
> >> http://mythtv.org/cgi-bin/mailman/listinfo/mythtv-users
> >>
> >
> > Cal,
> >
> > That's an interesting take on the use of XvMC.
> > My opinion is use a specialized tool for a specialized job.
> >  The XvMC circuitry on a video card is specifically designed to assist
> in
> > some of the heavy and specific tasks required in decoding mpeg2, as such
> > it
> > is likely to do this much more efficiently than a general purpose CPU
> is.
> > If you take this idea to an extreme you get a full hardware decoder such
> > as
> > that on the PVR-350, which only uses a very small heatsink (read low
> power
> > consumption) compared with the large heatsink (and fan) required for
> your
> > average CPU. (All other issues with the PVR-350 aside)
> >
> > That said XvMC does introduce some complications (as you point out):
> >      1) Driver support can be "fussy".
> >      2) The black and white OSD problem.
> >      3) It only works for MPEG2 at the moment. So if you want to play
> > anything other than MPEG2 then it's useless. This is particularly
> relevant
> > if you're looking at HD support.
> >
> > So basically if you're only decoding MPEG2 (or just SD) then XvMC is
> still
> > likely to be usefull, taking some load off your CPU for other tasks. ( I
> > currently run on a PIII 900Mhz so I like to offload whenever I can).
> >
> > Just my opinion mind...
> >
> > Cheers
> >
> > Steve
> > _______________________________________________
> > mythtv-users mailing list
> > mythtv-users at mythtv.org
> > http://mythtv.org/cgi-bin/mailman/listinfo/mythtv-users
> >
>
> Hmm
>
> Just when I'd decided to go with an underclocked 8500 GT (forgetting about
> XvMc, and thinking of gap size, and power consumption.
>
> Still confused.
>
> Running a dual opteron 2,4 Ghz, so have the CPU cycles. Just trying to
> keep power and temp down.
>
> Cheers!
>
> M.
> _______________________________________________
> mythtv-users mailing list
> mythtv-users at mythtv.org
> http://mythtv.org/cgi-bin/mailman/listinfo/mythtv-users
>

Well if you're going to have the CPU cycles anyway you might as well ditch
the XvMC as
Cal is spot on in that it does cause a few headaches re: drivers &
compatability etc.... so you'll have an easier time with things if you do.

Cooling is slightly more complex! By making the CPU do all the work you're
concentrating the heat in one place (the CPU), this means your CPU will run
hotter which is harder to cool quietly.

On the other hand you only have to worry about cooling one thing. The folks
on SilentPCReview may be able to help you with recommendations on cooling &
powerconsumption. Graphics cards have historically been power hogs, and are
only just starting to roll in lower power designs (like has been happening
recently with CPUs like the Core-duo).

Of course the other thing to think about is that instead of XvMC the
mythtv-vid branch is developing OpenGL rendering, which is again trying to
use the graphics card to do some heavy lifting!

I'm not being very helpful am I!?!

It depends what you're trying to do really.

Cheers

Steve
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