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Introduction:::...

It 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.

So 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.

Between 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!

With 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.

The 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.

Today's 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.

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!

He 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."

Their ethos is sound, now how about their products? First, the specs and a quick reminder of the main features behind the GPU:

GeForce 6800GT 256MB

Features:
• 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

System requirements:
• 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


OS Support:
• Windows® XP
• Windows® MCE
• Windows® 2000
• Windows® ME
• Windows® 9X
• Windows® NT4 SP6
• Linux

The Technology:::...

This 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.

CineFX 3.0 Features

Displacement Mapping:::...

I'm 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 raised.

This 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.

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 lighting.

Vertex Shader 3.0:::...

Vertex 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.

Displacement Mapping is available to the 6800 as a direct result of its shader functionality.

Vertex Frequency Stream Divider:::...

Say 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.

Multiple Render Targets:::...

Also 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.

Deferred 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.

In 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 scenes.

So What?:::...

32 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.

Pixel Effect Features

Rotated Grid Antialiasing:::...

If 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 in particular.

HPDR:::...

If 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 highlights.

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 critical.

UltraShadow II :::...

In 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 results.

The 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.

There's 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

If you're still awake you'll be glad to know that's the last of the techie talk. Now let's examine the hardware: