Product Reviews

They're here at last. After numerous rumours and leaks on the wires, and enough spin to make Alistair Campbell write a congratulatory memo, both ATi and nVidia have put their silicon where their mouths are. And let's be straight from the start: both companies have upped the ante to a truly astounding extent.
This shouldn't be too surprising, as the two reference samples reviewed here are each manufacturer's high-end offering for this year. They're built to last for the next 18 months, which in 3D card terms is several lifetimes.

nVidia GeForce 6800 Ultra
nVidia has decided to drop the FX moniker from its cards, one of the primary reasons being that it was 'unlucky' for them. The 6800 Ultra, formerly codenamed NV40, is a far bulkier beast due to a double-thickness heatsink and fan cooling system that will block the first PCI slot on your motherboard. It's still far lighter than the previous generation, though, despite packing a frankly absurd 220 millionÊtransistors.
The 6800 Ultra requires two Molex power connectors, and nVidia recommends that neither of these be in tandem with other components such as optical drives. It also requires a 450W power supply or above, so the majority of PCs will need to be upgraded. We'd cite this as a major flaw, but given the expense and quality of the card on offer here, an extra £20 on a new power supply seems a small price to pay.
And what an impressive specification it is. The GPU's clock speed may be lower than we'd expect, at 450MHz, but at least this gives plenty of space for the chip to be overclocked, be that by nVidia, the likes of Gainward or the owner. As with the ATi, there's 256MB of memory, but it's clocked slightly lower at 550MHz. It's also GDDR3 memory, originally developed by ATi, which runs on a specification designed for point-to-point graphics implementations. Its use in tandem with the enormous transistor count will likely explain the heat produced and therefore the need for such a large heatsink and fan combination.
While ATi merely put a digital video-in connector on the back of its reference design, nVidia has gone the whole hog and included an in-chip video processor. The main aim behind this is to take all the video processing away from the CPU, so it can dedicate its time to other tasks. We'll see why keeping the CPU as free as possible is so vital later. As well as basic video-processing features, editing support for MPEG-4 (including DivX), MPEG-2 and WMV9 (Windows Media Video 9) is included. This power will also allow for simultaneous playback of multiple video streams and time-shifting for PVR (personal video recording) purposes.
As with the ATi, DirectX 9b is supported, but nVidia has gone a stage further and provided support for Shader Model 3. This will be part of DirectX 9c and provides support for far longer shader programs that will allow for greater overall detail. While this makes no difference to the current crop of games, it's likely to have an impact on the next generation of titles, and is therefore very welcome. Finally, it also means dynamic branching is supported, while it isn't on the ATi chip. This means that the 6800 can skip complex shading instructions on irrelevant pixels, so it doesn't waste time shading darkness, for example.
Details

Crunch Time
As was very obvious last year, the on-paper specification of a card doesn't necessarily mean it's the fastest; ATi cards were consistently weaker on paper but regularly outshone the GeForce FX cards in benchmarks.
To start with, we tested the two cards on our testbed; this consists of a 3.2GHz Northwood Pentium 4, 512MB of memory and a 160GB hard disk. Both cards returned frame rates of around 50fps (frames per second) in Unreal Tournament 2004 and 35-40fps in Halo. Both tests were performed at 1,280 x 1,024.
When we upped the settings to 1,600 x 1,200, set AA (anti-aliasing) to 4x and AF (anisotropic filtering) to 8x, the frame rates barely changed. This was a clear sign that the CPU, rather than the graphics chip, was the bottleneck in performance. This was further proved when we transferred the cards to an Athlon 64 PC, with a chip that had been overclocked to 2.5GHz. There was a clear increase in performance.
We also tested the two cards in a set portion of Far Cry at 1,600 x 1,200, 4x AA and 8x AF, with all other settings pushed to maximum. The ATi managed to churn out an amazing 42fps, with the nVidia trailing slightly behind at 38fps.
However, we found little to separate the two cards when it came to performance, with the ATi coming only slightly lower in Unreal Tournament 2004. It was only when running 3DMark2001 SE at 1,280 x 1,024 that the cards separated in performance, with nVidia's chip losing out by around 12 per cent. Then again, given the age of that test, and the fact that it's synthetic, this is only a minor win for ATi.
So as was the case in the previous round of the ATi vs nVidia battle, test results give no real winner: both score incredibly highly, beating each other in a similar number of tests, and only marginally anyway.

Future Proof?
From these scores, it's clear that both cards are way ahead of their time - if even high-end 64-bit PCs can't run fast enough for them, there's no doubting they'll be able to cope with any game for at least the next 18 months.
It's important to note that these are merely AGP 8x versions of the cards. Versions using PCI Express will start to emerge in the coming months; roughly the same time that PCI Express-equipped motherboards are released. Only then, and with the advent of faster CPUs, will these two chips be able to demonstrate how fast they really are.
Another thing to bear in mind is that both manufacturers tend to hold back on the technology; the first release of a new generation is never the best. Take, for example, the FX 5900 XT from nVidia, which was very powerful and exceptional value. So it may be worth holding out for the next generation, especially as the games that can truly take advantage aren't even here yet.
Also, just as we went to press, nVidia announced a 'GT' version of the 6800 chip that will run at 350MHz core and with 500MHz memory. It will also have 16 pipes, making it potentially more powerful than ATi'sX800Pro.
But what if you can't wait? Well, opinion in the PC Pro office was divided; those traditionally loyal to the nVidia camp stuck firmly to the GeForce family, claiming that slightly inferior performance was an acceptable loss in favour of the future-proofing that its features provide. Those loyal to ATi also remained faithful, citing its superior 'bang per buck' as the principle reason. However, with pricing yet to be confirmed, it isn't yet possible to make a concrete decision.
Cards with both chips are expected to go on sale in July - look for reviews of retail versions of the cards in subsequent issues of PCPro.