The
7800GTX 512mb is not the smallest of cards,
as soon as you remove it from the packaging you know
this is a card that means business. Unlike the
original GTX reference design the 512mb model uses
a dual slot cooler. As far as heatsink/cooler designs
go this is certainly one of the more impressive designs
we've seen. The heat is absorbed by the heatsink directly
under the fan and heatpipes dissipate this to the
fins which are located at the left and right of the
fan. Due to the positioning of the fan it pushes air
across the fins to help keep them, and the card, cool.
As you can
see from the above picture the GTX uses a rather meaty
looking fan, due to this its initially worrying that
the quiet operation of the 256model would be at risk,
however im pleased to say that isn’t the
case and the 512mb model is just as quiet, if
not more so. In a room ambient of 27 degrees and a
case temperature of 44 degrees the idle temperature
of the GTX was around 50 degrees. After a testing
session we checked again and the core temp had raised
to 63 degrees, however the fan had remained near silent
at all times.
The first thing
that is obvious about the new GTX, even from reading
the name is the move from 256mb to 512mb of GDDR3
memory. By removing the heatsink you can see that
Nvidia are using Samsung chips and there are eight
64bit chips in use on this model.
On the reference
model they are cooled by the heatsink and the thermal
material used is almost fabric like, stringy and mildly
sticky. It does its job well though.
By removing
the cooler you can see the core of the card which
is a G70 chip and additional power, through the 6pin
PCIE power adapter is required. What’s also
noticeable is that there is a 2nd heatsink underneath
the main one which keeps some additional components
cool.
The rear of
the card is very similar to the GTX 256mb, you can
however see the SLI connector more easily.
Connectivity
is provided in the form of 2DVI connectors and the
usual video out port which supports the usual standards
such as s-video and HDTV out (1080i). As the GTX supports
Purevideo you are guaranteed that the output quality
to your display is very high quality and
with additional features such as 3:2 and 2:2 pull
down and advanced scaling and de-interlacing Purevideo
allows even non HD source material to look great on
your advanced display.
What looking
at the card doesn’t tell you however are the
core and memory speeds. By remaining at 24 pipelines
in addition to adding 256mb to the spec Nvidia were
also required to increase the core and memory speeds
to attempt to pass ATI in the speed stakes. So rather
than 430mhz/600mhz of the original GTX reference design
we have a card which is clocked at 550mhz on the core
and 850mhz on the memory. That’s right, not
only have Nvidia released a card which pushes the
G70 core up by 120mhz they are also bumping the memory
up by a whopping 250mhz. On paper this is one hell
of an increase and it is clear Nvidia are out to prove
a point.
As we mentioned
earlier, the GTX 512mb is based on the G70 core and
so is a .11micron part with 8 vertex units and 24
pixel pipelines. This means that all of the advanced
features of the original GTX are still present. The
card supports Shader Model 3 and
therefore HDR lighting. There is
full 128bit floating point
support throughout the architecture and the
core and memory are connected by a 256bit
bus.
Transparency
Anti Aliasing (multi and super sampling)
are also still present in the feature set and as well
as supporting V8U8 compression the
GTX also supports 3DC compression.
So that’s
Nvidias Geforce 7800GTX 512mb, a very impressive product
on paper I’m sure you'll agree.
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