[mythtv-users] Need help picking out new motherboard / cpu
jcw at wilsonet.com
Tue Mar 30 03:30:43 EST 2004
On Mar 29, 2004, at 23:17, Kevin D. Snodgrass wrote:
> James Armstrong wrote:
>> I have the useless Via133 chipset and need a new backend / frontend. I
>> was going to use my Athlon 900 for the backend and get a new frontend
>> capable of playing HDTV until the 900 started having DMA problems. My
>> question is, what will I need to have a combined backend/frontend
>> capable of recording from two PVR250's and one pcHDTV card and watch
> Note: I don't have my MythTV box built yet. All parts are in except
> the case/power supply. (ARRRRGH!) But I have read about this stuff
> for several months and had to do essentially the same evaluation you
> are currently doing.
> The PVR-250s don't really take any CPU time, the do all the heavy
> lifting on-board. I don't know about the pcHDTV, but I think it has a
> hardware compression chip built-in so it shouldn't stress the CPU much
Very little heavy lifting required for capture with the pcHDTV, but not
because it has any hardware compression. HDTV is nothing but an
mpeg2-transport stream, which the pcHDTV simply tunes to and writes out
to disk. All the encoding/compression was already done at the broadcast
> Watching is a different matter, but it still isn't going to stress a
> modern CPU too much.
Standard-def TV won't, but HDTV will. A common recommendation is for a
3GHz HT P4. I have an Athlon XP 3200 for this very reason, but haven't
played with my pcHDTV card in ages...
>> the same time? Will one of the following processors be better: P4
>> HT with 1Meg cache, P4 3Ghz HT 512 cache, P4 3.2Ghz HT 512 cache.
> I think those are all overkill for 2 PVR-250s and a pcHDTV. But
> better too much than not enough, right? I opted for an AMD 2800+ and
> 512 MB RAM for my 3 PVR-250s since I expect to do commercial cutting
> and burning to DVD on the same system.
I've seen flawless playback of full-rez, high-bitrate PVR-x50 captures
on an Athlon 800. But no, those P4 chips are about the right ballpark
for flawless HDTV playback. I'm not certain what the difference would
be between the 2.8 w/1MB cache and the 3.0 w/512. I don't know enough
about the HDTV decoding process to know if more cache or more raw
processing power is better.
>> are also the order of lowest to highest price. The difference is not
>> much, will the 1meg cache make more difference than the higher speeds?
>> Is 200Mhz more speed worth $60? Can I have three tuners (one being
> I don't think the extra $60 will matter.
Dunno. I'm thinking the 2.8 should be fine. You can definitely have 3
>> and possibly record from all and watch tv too (HDTV being worse case)
>> will I still need a dedicated backend?
I believe any of those P4 chips should be able to handle everything.
> Well, you can't record on all your turners AND watch TV via one of the
> turners (unless you are watching what one of the turners is recording)
> all at once. You are short one turner there.
Yes, worst-case being the 250s recording, and the pcHDTV either
recording with you watching it or viewing live TV with it, you should
be fine. None of the recording takes much CPU, the big hit is the HDTV
Jarod C. Wilson, RHCE
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