Product Reviews

When Nvidia unveiled the GeForce3 in February 2001, it was the first card to use Pixel and Vertex Shaders for high-quality 3D. Since then, the competition has caught up, and ATi's Radeon 8500 (see Reviews, issue 86, p169) has overshadowed the GeForce3 thanks to similar 3D and better 2D performance. Nvidia's swift response has been to replace the GeForce3 - less than a year into its lifetime - with the GeForce4 Ti 4600.

The GeForce4 comes in two flavours - the GeForce4 Ti and GeForce4 MX - with various specifications in each type. The GeForce4 Ti replaces the high-end GeForce3, and the GeForce4 MX replaces the budget GeForce2 MX. Both cards share similarities, but have key differences, which we've explained in the MX review opposite.

The GeForce4 Ti is aimed at the power user and gamer. The flagship Ti 4600 is essentially the Ultra version, featuring AGP 8x support and speeds of 300MHz for the core and 650MHz DDR for the memory. In addition to this, the GeForce4 Ti boasts 128Mb of memory and a number of other key improvements.

With 3D games becoming more complicated, the demands on memory bandwidth rise, especially at high resolutions with anti-aliasing. Nvidia combated this in the GeForce3 with LightSpeed memory architecture. The GeForce4 takes this a step further with LightSpeed II.

The GeForce4 Ti uses a similar crossbar memory controller to the GeForce3. Four independent controllers access data in 64-bit, 128-bit or 256-bit chunks, the benefit being that smaller data fetches don't utilise the entire bandwidth. And as the controllers operate independently, bandwidth use is more efficient.

Other bandwidth-saving features include the Quad Cache subsystem. This refers to four individual high-speed data buffers, with one each for storing primitive (triangle), pixel, texture and vertex information. Depending on how successful these optimised caches are, bandwidth requirements could be significantly reduced, as cached data won't need to be fetched from memory or recalculated.

Also new is Fast Z-Clear, which minimises the time taken to clear old Z data. As each pixel has a Z value (essentially used to determine if a pixel is visible), clearing this can consume lots of bandwidth. Nvidia claims fast Z clearing alone can boost frame rates by up to 10 per cent. Like its predecessor, the GeForce4 has lossless Z compression of 4:1.

New too is Auto Precharge, which actively readies soon-to-be-used banks of memory, cutting down the number of clock cycles wasted before data can be accessed.

Finally, Nvidia has improved its Z-occlusion culling system to further reduce the number of hidden pixels rendered (such as a car behind a wall). The GeForce4 uses a new algorithm, claiming to be more effective than the GeForce3.

Another major change with the GeForce4 Ti is nfiniteFX II, introducing two parallel Vertex Shaders. This, in combination with the higher clock speeds, boosts the GeForce4 Ti's vertex processing capability. In fact, Nvidia claims a three-fold increase compared with the GeForce3. As animation complexity increases, the GeForce4 Ti will be well placed to cope.

On the flip side, nothing much has changed

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in the Pixel Shaders, which are used for operations such as colouring, texturing and applying special effects on a per-pixel basis. Nvidia again uses version 1.1 Pixel Shaders, unlike ATi, which uses the DirectX 8.1-supported version 1.4 for the Radeon 8500. While 1.4 adds more functionality, it's likely Nvidia chose 1.1 for continuity, as programming for 1.4 is slightly different. Nvidia has also modified how the Pixel Shader engine functions, claiming the GeForce4 Ti can be up to 50 per cent faster than the GeForce3 in this area.

Accuview is a new anti-aliasing system utilising an improved algorithm and an optimised pipeline, with subpixel rendering performed in parallel, saving time and bandwidth. Accuview introduces a Direct3D 4xS mode, which shifts where subpixel samples are taken from in order to reduce colour errors. The 4xS mode also claims improved texture quality and incorporates anisotropic filtering, which considers the optical angle and helps improve the texture quality of objects that extend from the near distance into the background.

We tested 4xS and found that image quality was improved. Performance suffered slightly, though, compared to the normal 4x mode.

That said, the GeForce4 Ti 4600 isn't lacking in performance. The overall PC Pro 3D score of 2.6 (see opposite for full test methodology) is stunning, blowing away the Radeon 8500, which scored 2.0 and even Nvidia's own GeForce3 Ti 500 (see Reviews, issue 86, p171), which scored 2.09. Part of the reason for the Ti 4600's fine performance was its anti-aliasing test results. A score of 5,383 in 3DMark2001 in XGA in 32-bit colour with 4x anti-aliasing is amazing.

But the GeForce4 isn't finished yet. Not only does it boast improved performance, but, for the first time, it also bundles high-quality video capabilities and multiple monitor support.

The VPE (Video Processing Engine) gives the GeForce4 much-improved DVD playback and TV output capabilities. The engine boasts motion compensation, IDCT, IQ and CSC for accelerating DVD decoding. The VPE's video-processing capabilities also include features such as adaptive deinterlacing and scaling and filtering for optimising image quality at different resolutions. There's also Nvidia's Digital Vibrance Control. In addition, VPE provides support for HDTV (also a feature of the GeForce2 and 3), and its hardware features aid applications like time-shifted video. There are dual ten-bit 350MHz RAMDACs and TMDS transmitters for digital TFTs. Interestingly, the VPE has dual CRT pipes, which drive independent graphics/video data and can even be used for dual monitor gaming with full DirectX and OpenGL acceleration.

We watched a number of DVDs using the GeForce4 and the quality is much improved over the GeForce2 and 3 and on a par with the Radeon 8500. DVD has previously been a weakness of Nvidia cards, so it's welcome here.

Finally, there's nView, Nvidia's solution for multiple displays - again previously omitted from its higher-end cards. Nvidia's solution provides the usual Desktop-extending features as well as integrating with various applications. For example, right-double-clicking on a hyperlink can open the URL on the second display. Also, nView allows for separate user profiles, up to 32 switchable Desktops, transparent windows and zooming. This is a great value-adding feature.

The GeForce4 Ti 4600 is an amazing graphics card, aimed at the power user who must have the latest and greatest. In terms of 3D, it doesn't do anything the GeForce3 can't; instead, it does it much faster, with greater anti-aliasing flexibility. The new 2D and dual display capabilities are long overdue too. The GeForce4 Ti 4600 is quite simply the most powerful mainstream graphics card available today.