The first examples of the new PCI Express graphics cards are hitting the shelves, but for now they are all aimed at the mainstream and value segments of the market. High-end PCI-E cards are on their way, but because the demand for high-end AGP cards is still high, expect a trickle more than a flood when they do start appearing.

PCI Express is the next generation bus that offers much faster data transfer than the PCI bus we are all used to at the moment. Because it uses a serial data transfer scheme it offers the potential of much higher clock speeds than the current PCI bus, and being serial means that the data rate is usable in both directions simultaneously.

The x16 PCI Express bus means it has 16 channels which, when added together, gives a peak duplex bandwidth of 8GB/s (4GB/s in each direction). But as graphics performance only relies on data transferring in one direction, the pertinent figure is 4GB/s. Twice the bandwidth of AGP 8X it may be, but it's going to be a while before this performance shows up in games.

ATI's mainstream PCI-E reference card is the X600, available either as the XT or the Pro. Despite the name, the RV380 core is not a cut-down version of the X800, but is based on the RV360 core used on the Radeon 9600XT line-up. The X600 has a core speed of 400MHz, while the memory clock runs at 600MHz DDR. The memory uses a 128-bit memory bus while there are just four pixel pipelines.

Sapphire's X600 is a reference ATI design and comes with either 128MB or, as on the card reviewed, 256MB of 128-bit Samsung memory. Because ATI has a native solution for the PCI-E bus (Nvidia uses a bridge chip between the AGP and PCI-E bus which needs the addition of a heatsink), the card has just a small cooler on top of the GPU, with the memory chips left void of any cooling.

When it comes to performance the PCI-E bus adds nothing to the original 9600XT - with a default 1024 x 768 3DMark03 score of 3,477 and a FarCry score of 34.50fps - since the card's processor isn't really capable of straining the 8x AGP bus anyway. New, faster processors will.

Sapphire bundles full versions of Prince of Persia and Pandora Tomorrow with the X600, along with PowerDVD, Power Director and Sapphire's Redline overclocking utility. Hardware-wise you get the usual DVI-I adapter and all the normal cables.

If you plan to use a motherboard with the latest i915 or 925X chipsets from Intel, then the X600 is about the best card to bide you over until the higher end cards begin to make an appearance.