[mythtv-users] 8400GS -> GT 430 -> ?? (60Hz, VDPAU High Quality)

[Christopher Kerr]

On 6/21/12, Gary Buhrmaster <gary.buhrmaster at gmail.com> wrote:
> On Wed, Jun 20, 2012 at 4:24 PM, Christopher Kerr <mythtv at theseekerr.com>
> wrote:
> ....
>> GT640's are just starting to become available as desktop cards - they're
>> based on chips intended for laptop usage, so I expect a low-profile
>> version
>> will be along shortly. They should be ~40% faster than GT440's (which are
>> basically just factory overclocked GT430's) which would make them strong
>> contenders as HTPC cards if a fanless version shows up.
>
> There is "faster" and there is "faster".  For many applications, the
> GT430 is "faster" than a GT220, but not for running the de-interlacer
> code (the improvements are elsewhere).  Any recent nVidia card
> can do decoding of the usual codecs (mpeg/h264) via dedicated
> hardware.  The code that does the deinterlacing runs in the
> stream processors, and how many are needed, at what clock
> speed, is highly dependent on not only your content type but the
> nVidia stream processor architecture.

As you note, comparison is difficult. The GT430 has 96 Fermi-type
shader cores clocked around 1.4GHz. The GT640 has 384 Keplar-type
shader cores, which are substantially different and don't use an
independent clock (but for reference, they're clocked, along with the
core, at 900MHz).

Both have a 128-bit memory bus supporting DDR3 at 1.8GHz effective data rate.

So I'm optimistic, but right now I have no proof.

> I have seen no
> evaluation of the GT640M (the M is important) in regards to
> its capability

The M is less important for this particular card than you'd expect, as
the 640 uses the same (GK107) chip - the 640M just complicates matters
by throwing in a slower base clock with "Turbo" modes.

(To further complicate matters, there's also the GT630, which is an
OEM part which is basically the GT640M on a desktop card. Even more
confusingly, it used to be called the GT640, until nVidia renamed it
when they introduced the current GT640....)

> The nVidia triad for Linux HTPC:  Low-profile, fan-less, able to
> perform Advanced 2X de-interlacing for all content in 60Hz
> countries.  Pick any two (well, that is slightly unfair, since
> there is other criteria such as HDMI audio, and the presumption
> that fan-less does not include cooling solutions such as
> water heat transfer, and you are not going to do SMT rework
> to change the card layout, etc.)

I think this chip MIGHT be capable of hitting all of those points
provided you don't mind having a rather large passive cooler. Whether
anyone will build such a card remains to be seen.

- Chris