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Introduction:::...

If there's one thing a rash of new product launches means it's that you'll have to learn a whole new batch of model numbers, prefixes, suffixes and acronyms. Just in the graphics card arena so far this year we've had to come to terms with "Ultras", "Pro's", "GT's", "XT's", "XT-PE's", "PCI-E" and "GDDR3", and the year's not done yet!

The letters we're concerning ourselves with today are "XT-PE", or to put it in simple terms, the fastest Radeon X800 your money can currently buy you. The PE denotes that the card is a "Platinum Edition" version, and as we'll find out shortly, the "XT" must surely stand for "Xtremely Tasty"?

The Radeon X800 XT-PE I'm looking at today was supplied one of the smaller fish in the pixel pond, Connect3D. Despite being a less prominent player, Connect3D have consistently produced high quality products at great prices and are known for their general "no frills" approach by catering to those who favour value for money over free, and possibly duplicated software titles and dubious in-box incentives. With 600 employees and a manufacturing presence in Zhenzhen, China however, Connect3D are no fleeting presence. They may not have the marketing clout enjoyed by some of ATi's bigger first-tier partners but have no doubts about their capabilities, either to supply the products or to support them.

Heading up ATi's latest generation of graphics card, the XT-Platinum Edition has the full compliment of 16 pipelines throwing data through them at 520 million cycles per second and feeding 256MB of DDR3 memory running at 560million Hertz (560MHz) which is 1.12GHz effectively. It doesn't seem so very long ago we were all celebrating the first CPU to run at 1GHz!

If you've yet to see an X800 in the flesh you're no doubt expecting it to be a rather industrial looking dual-slot part with more power connectors than memory chips and with the dimensions of a small dining table, but as we'll see on page three it's in fact a very elegantly engineered piece of kit that's no bigger than the earlier 9800XT.

For those of you who are familiar with the technical details of the X800 please skip over to the next page. If you want a quick reminder of what the X800 is all about here's a quick recap from some of our previous reviews.

Features:

• 256MB of 'Xtreme performance GDDR3 memory accelerates the latest cutting edge 3D applications
• 256-bit quad-channel GDDR3 memory interface
• Twelve 'Xtreme parallel pixel pipelines
• Supports the AGP 8X and AGP 4x standard, providing a high-speed link between the graphics board and the rest of the PC
• Six programmable vertex shader pipelines
• Full support for DirectX® 9.0 and the latest OpenGL® functionality
• New SMARTSHADER™ HD technology allows for support for Microsoft® DirectX® 9.0 programmable vertex and pixel shaders in hardware as well as OpenGL® via extensions.
• SMOOTHVISION™ HD technology provides enhanced image quality by removing jagged edges and bringing out fine texture detail, without compromising performance
• 3Dc™ High quality 4:1 Normal Map Compression delivers beautiful scenes without the performance hit.
• Unique VIDEOSHADER™ HD engine uses programmable pixel shaders to accelerate video processing and provide better-looking visuals
• HYPER Z™ HD is optimized for performance at high display resolutions, including widescreen HDTV resolutions.

The RADEON™ X800 PRO must be connected to the computer? power supply to meet its performance and high-speed memory requirements.
In order to supply the ATI Graphics Accelerator card with the necessary power, we have included the Power Extension Cable.
Use the Power Extension Cable to connect the Radeon X800 PRO to the computer? hard Drive power connector.

The Technology:::...

Let's not pull any punches here, the R420 isn't a massively different chip to its predecessor the R300. There are however a few important additions and refinements so before we move on let's take a quick look at the more important ones.

3Dc:

Short of building even the most simple of objects from many tens of thousands of polygons, the best way to add detail to the surface of an object is though the clever use of high resolution textures or manipulation of the available lighting information. Imagine a low ploygon model, it looks angular and false. Now drape it with a high quality texture and suddenly it loses some of its angles and starts to resemlble what it's meant to be. At this stage though the texture still looks flat and lacking any depth and real detail.

Rather than pump up the polygon count, a far lest costly way to increases surface detail is to use high resolution normal maps.

A Normal is a piece of data showing the way in which light interacts with a surface at a given point. The problem is that models made from too few polygons contain too few normals to create a properly lit surface. What 3DC does is to create a high resolution normal map which stires vastly more information than would normally be generated and then apply that to the object, so giving the illusion that it contains far more detail than it really does.

Because this method uses pixel operations rather than geometry functions, it tends to be more efficient on consumer graphics cards which are often optimized for pixel data throughput.

Of course the benefits from 3Dc are slowly being eroded as polygon counts and texture quality inreases in modern games but ultimately it's a feature worth having. 3Dc works on any two-channel data formats and is not particularly limited to normal maps.

Temporal AA:::...

One of the big features introduced with ATi's CATALYST 4.7 drivers was the mysterious Temporal Antialiasing setting.

I've covered the principle before but for those who've not heard, Temporal AA works by staggering its sample patterns across two frames of animation. What this means is that frame one performs a 2x antialiasing calculation and frame two carries out the same procedure but samples from alternative positions. The end result is that two slightly different frames are created which, provided they are displayed quickly enough, combine to give the illusion that it's all happening in a single frame. Enable temporal AA and in theory you get twice the level of antialiasing you've actually set. Ingenious!

DX9 FSAA Viewer 5.1 does a nice job of showing the two sample patterns. In this case I used a 4xAA setting though by far the most effective, and in many cases useful setting will surely be the 2x setting. This allows near 4xAA quality under the right conditions but with only the performance penalty normally associated with a 2x sample pattern.

Of course it's not all good news. The problem with this method antialiasing is that when framerates drop to a low enough level there's a very visible and slightly distracting edge flicker as the transitions between odd and even frames starts to become an issue. This, as you might expect, becomes more of a distraction with high contrast edges. Ironically this is more of a problem using modern monitors with their low persistence phosphors than it would have been with older displays which weren't quite so quick to switch their pixels.

ATi have partly dealt with the flicker issue by having the drivers disable Temporal AA as soon as framerates drop below a fixed threshold, currently 60fps, but this in itself can cause distraction as, in some games, the switching becomes quite noticeable. I'm not sure if it's a physical lag or just that it catches the eye but it is visible in some games, and less so in others.

The rather enlarged example below is from an edge that was originally angled but has been placed horizontally here for ease.

Animation Showing Odd and Even Frame Edge Pixels

I can't get the animation to run at the 100 plus frames per second needed to get a reasonable effect but if we shrink the selection down and speed it up as much as possible you can hopefully get an idea what Temporal AA achieves.

As you'd expect it's impossible to grab a screenshot of the effect in action as a single frame will always be using one or other of the two sample patterns, and I'm not certain that combining and averaging then would give a true representation of what you actually see in-game. Temporal AA is however a worthwhile feature and when used in the right situations the effect is extremely impressive. I'd like more control over the threshold level personally but maybe that will come. I'm also curious to see what other advanced effects could be "shared" across multiple frames, perhaps super hi-res textures or complex ray tracing effects?

Testing the performance hit, if any, is something else we'll belooking at. The problem here is that in order to use Temporal AA, you need to have VSync enabled which impacts on the results. Even with a 120Hz refresh rate I wasn't able to find a benchmark that would run consistently at between 60 and 120 fps for the duration.

Other than the occasional flickering, the only problem I encountered with TemporalAA was that in one, isolated incident, it seemed to introduce an element of moiré into a scene where one of the textures featured tightly packed diagonals and I'd be curious to hear if anybody has noticed anything similar in any other games titles or whether this was an isolated event.

High definition gaming with up to 16 pipelines, up to 80 concurrent shader operations per clock, 6 vertex shaders delivering in excess of 750million vertices per second, improved Centroid sample and new Temporal Antialiasing plus FULLSREAM video deblocking, HDTV support, HYPER Z HD and more, and all in a single slot solution.

Sound tempting? Let's look at the hardware.