[mythtv-users] Which NVidia card

Marius Schrecker marius at schrecker.org
Mon Jan 21 15:14:42 UTC 2008


> 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?)
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>>
>
> 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
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>

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.


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