Intel SandyBridge... I don't get it.

[Lennart Sorensen]

On Thu, Jan 27, 2011 at 12:46:25PM -0500, D. Hugh Redelmeier wrote:
> Interesting that you should say this.  See the end of this message to
> see relevance.
> 
> I'm agonizing about building a new MythTV backend.
> 
> I want lots of PCI slots to hold my Hauppauge analog tuners.
> (my current box had 5 tuners but is down to 4 since I needed to add
> a SATA contoller)
> 
>     + I don't want to spend a lot because who knows how long analog
>       signals will be with us (over cable)
> 
>     + I want to stay with analog as long as I can because DRM prevents
>       recording digital cable signals (the record-component-out hack is a
>       little hacky, but I will try that; it requires a lot of Rogers STBs
>       and whacky open-loop control of the tuner)

Open loop?

> It's come down to these choices:
> 
> - use an ancient PC from inventory (lots of PCI slots, PATA, low
>   horespower)
> 
> - build a new box out of socket 775 motherboard:
>   <http://www.gigabyte.com/products/product-page.aspx?pid=3637&dl=#sp>
>   5 PCI; cheap; obsolete; DDR3
>   Need to also buy CPU and RAM.
>   Variant: there is version that uses DDR2; I have some DDR2.
> 
> - build a new box out of a used socket 1156 board that is available
>   4 PCI; used price == 775 board's new price; USB 3.0, more PCIe slots
>   Need to also buy CPU and RAM.
> 
> - use a semi-current AMD box I've already built
>   3 PCI (the most AMD boards seem to offer)
>   3 is too few, I think.
> 
> So: how much better are 1156 systems than 775 systems (and Socket AM2+
> systems) for my purpose?

Depends what you are doing.

> Will 5 SD streams swamp + whatever Myth is doing swamp the memory bus?
> If so, 1156 would be much better.

Well if you use hardware mpeg2 compression cards, then I doubt it would
be much load at all.

> Will anything need much CPU?  Since I've been living with an Athlon
> 1700 XP, I think the CPU issue is minor.  I do hope to add a couple of
> Hauppauge HD PVRs and I don't know what load that adds.

The HD PVR compresses to MPEG 4 in hardware, so the data isn't that much,
although USB being extremely inefficient may take a decent chunk of CPU
to handle.

Of course there are crazy solutions out there:
http://www.magma.com/4slot.asp

Box with 4 PCI slots, attaches by cable to the host and uses one slot
there (PCIe or PCI, your choice).  Too bad it is stupidly expensive
($1500).  It would be cheaper to build multiple backend machines with
a couple of PCI cards each.

Another method is a PCI bridge riser like this one:
http://www.orbitmicro.com/global/rc2-019-p-686.html
Turns one PCI slot into 3 slots.  Add a PCI extender cable and you could
actually use multiple.  How you mount the cards in the case is another
interesting issue then.

-- 
Len Sorensen
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