may feel like the whole world has already made the switch
to PCI-Express but I can assure you that's not the case.
AGP is alive and well and likely with us for some time yet.
That said, it would be foolish to shun the PCI-E standard
if you have an upgrade planned, I just wouldn't go selling
any vital organs just to buy in at this stage of its evolution.
We haven't had the pleasure of seeing AGP working to its
potential yet and already we're being asked to fork out
for yet another new performance-enhancing technology based
on nothing but promises.
assuming you're sticking with AGP which graphics card should
you buy? Well, power users with an expensive taste will
no doubt be aiming for a 6800 Ultra or an X800XT Platinum
Edition. By the same rule if your only requirement is something
that can display text and the occasional graphic on your
monitor you'll be trawling the stores and eyeing e-tailers
for lesser beasts like the Radeon 7XXX or GeForce 6200.
those two camps though live a band of gamers who want the
fastest GPU on the planet but who simply can't fund their
dreams, and for these users there's a constant battle to
find the ultimate blend of price and performance, even if
that performance isn't quite available right out of the
box, and by that I'm of course talking about overclockability!
both ATi and NVIDIA guilty of turning off pipelines and
fitting slower memory to their mainstream cards, it's not
quite as straightforward as you'd imaging to pick up a mid-powered
GPU and clock it until it squeals. Even so it seems that
from time to time a GPU makes it to market with all its
faculties intact and needing nothing more than a loving
tweak to make it do far more than it should for the price
you paid. And so it was with the GeForce 6800 GT.
6800GT was basically a slightly more pedestrian version
of the flagship 6800 Ultra. Clocked at 350/500 (Core/Memory)
as opposed to 400/550 for the Ultra, the 6800GT has all
16 pipelines available to it and also comes equipped with
a full compliment of 256MB GDDR3 memory. Just about every
6800GT produced could make it to 6800 Ultra speeds, some
could make it further. Either way it's a relatively cheap
way to get up with the big boys, provided they aren't overclocking
too that is.
review isn't so much about the technology. I think the virtues
of the 6800GT are fairly well known by now, even though
we cover the basics below. It's more about the company behind
the product, a company who have a very successful business
throughout Europe but who are only just beginning their
push on the UK market Read their press release HERE).
That company is Club3D.
are a bit of a rare bird in that its product portfolio includes
graphics products not only from NVIDIA, but also from ATi,
XGI and S3 too. This may optimise their marketing possibilities
but I wondered how it would impact on their relationship
with the individual companies. The answer I got from the
UK's Gary Jones was a very simple one...."it doesn't!
Our relationship as one of Europe's biggest partners gives
us unprecedented access to stocks even when numbers are
limited. We get what we need to be the best and we get it
first" he told me. Fair enough!
was also extremely candid about pricing and made it clear
to me that Club3D are not, and probably never will be the
cheapest cards you can buy. "We specify only the
best Japanese capacitors and highest quality Japanese board
level components" Jones told me proudly, "dirt
cheap isn't always the best way to go when it comes to complex
products like graphics cards. Reliability and performance
must come first."
ethos is sound, now how about their products? First, the
specs and a quick reminder of the main features behind the
• NVIDIA® CineFX™ 3.0 Technology
• Full support for DirectX® 9.0
• NVIDIA® UltraShadow™ II Technology
• 64-Bit Texture Filtering and Blending
• VertexShaders 3.0
• PixelShaders 3.0
• Up to 16x Anisotropic Filtering
• Up to 6x Multi Sampling Anti Aliasing
• Support for unlimited shader lengths
• Intel Pentium or AMD Athlon or compatible
• 128MB of system memory
• Mainboard with free AGP (4x/8x) slot
• AGP Voltage 1,5V
• CD-ROM drive for software installation
• 400Watt or greater Power Supply
• Windows® XP
• Windows® MCE
• Windows® 2000
• Windows® ME
• Windows® 9X
• Windows® NT4 SP6
integrated 10 bit per channel 400 MHz DACs
165 MHz TMDS transmitter
TV Output support up to 1024x768 resolution
complete list of resolutions depends on the driver version
and operating system.
NOTE: resolutions are limited by the performance of
the attached monitor.
is no longer a new architecture so there's not much point
going in going through it all in too much detail, which
I'm sure will please some of you. Instead we'll just touch
on what we feel are the technologies that matter along with
a simple look at how they work or what they do.
sure by now you've all heard of bump mapping. Bump Mapping
uses shading techniques to make flat surface textures look
like they have a a 3d surface when in fact they don't. Using
bump mapping, you can make the individual stones in a flat,
stone wall texture cast shadows as if they were actually
is okay in most situations but when lighting in a scene
is particularly complex, or when seeing a surface in profile
gives away its butt-smooth surface and spoils the illusion,
then something more is needed. That something more is Displacement
mapping takes a simple, profile map of an object then physically
changes the geometry so it matches the shape. In other words,
instead of the Dinosaur head below having "virtual"
wrinkles that don't properly interact with a scene's lighting
and don't actually exist geometrically, displacement mapping
creates real wrinkles out of the mesh of polygons that go
to make up the head. This results in more realistic surfaces
that can be viewed accurately from any angle and in any
Shader 3.0 adds infinite length vertex programs where the
operating system and API allows. Dynamic flow control can
intelligently allow routing of data within the rendering
pipeline so removing many of the previously imposed limitations.
Mapping is available to the 6800 as a direct result of its
Frequency Stream Divider:::...
what! Well, in layman's terms this lets programmers introduce
fixed, preset differences into batch animations. This is
almost like dialing in a controlled error or a variable,
so if you were animating a battalion of troops for example
each could be made to look slightly different by altering
anything from height, uniform colour or even the way they
move, the speed they walk at or even how high they swing
their arms when they walk.
known as deferred shading. There's no easy way to explain
this, but I'll try. For complex shading techniques, such
as per-pixel lighting techniques, it's often necessary to
send the geometry through the rendering pipeline more than
once before the final pixel colour is calculated. When the
scene being rendered is already complex, this expensive
multipass technique is often ruled out as it would simply
take too long to perform.
shading extracts all the shading data required for the final
scene and saves them to multiple attribute buffers. The
data from these buffers is then unpacked and applied to
the scene geometry after it has been calculated so saving
the need to resubmit it.
short then, deferring the shading/lighting calculations
allows you to apply complex lighting and shading techniques
while performing a single pass for normal vertex processing.
This allows intricate effect to be applied to even polygon-heavy
bit precision throughout the entire pipeline open up a world
of possibilities, but they're possibilities that won't be
used unless there's enough power to make them workable.
This time, I think that part of the equation may finally
be fulfilled, at least partly.
you look at the diagram below, the example on the left shows
the traditional subpixel sampling arrangement of a two by
two grid essentially only samples two horizontal and two
vertical values. By rotating the grid slightly as in the
example on the right, that can be increased to cover four
horizontal and four vertical values which should mean more
accurate subpixel colour sampling at the edge of polygons
you're a photography buff you'll probably understand this
feature easier if I explain that it's just like increasing
the latitude of your film. For the rest of us, it allows
a scene to have a greater range of brightnesses without
having to sacrifice details in either the shadows or the
scene on the left is rendered without HPDR and has a dynamic
range of about 100:1 while the scene on the right which
is rendered using HDPR and is closer to 9000:1. Personally
I think NVIDIA have chosen a really bad example of this
technology with these pictures as I happen to prefer the
image rendered without HPDR, but there are certainly situations
where the ability to effectively lower contrast would be
all the accusations of cheating it always struck me as odd
that nobody every considered UltraShadow to be a cheat too.
UltraShadow allows programmers to specify the zone within
which shadow calculations are performed. In the example
below, any shadows that fall in front of the near boundry
(zmin) or behind the far boundry (zmax) are basically ignored.
While this is a great technology in the right hands I can
imagine all kinds of scenarios where it could be wrongly
used to increase performance but with some fairly weird
buzzword here is "Superscalar". The term Superscalar
refers to the ability to execute more than one operation
per clock cycle, and the addition of a second shader unit,
the GeForce 6 is capable of up to four instructions and
eight operations per pixel, compared to just two instructions
and four operations in traditional architectures.
lots more we could talk about like the 222million transistors,
the dedicated on-chip video acceleration, the dual 400MHz
RAMDACs and the floating point frame buffer blending but
if these are things you're interested in you've no doubt
already read about them. Let's round
you're still awake you'll be glad to know that's the last
of the techie talk. Now let's examine the hardware: