XFX 8600 GT

Number 6

While Nvidia's previous DirectX 10 efforts have been mostly impressive, both in terms of performance and physical size, they've also been on the pricey side. What we've all been waiting for is the launch of the rest of the GeForce 8-series cards and, in particular, the 8600. Nvidia has a talent for designing high-performance GPUs for cards costing only £120 or so, as the six products on test prove. We'll have to wait until next month to get real-world prices for its AMD/ATi competitor - the Radeon HD 2600 - but these cards are on sale now.

8600 GTS vs GT

Before delving into the tests and how well the six cards dealt with them, let's briefly cover the theory behind the performance. Architecturally, there's no difference between the GTS and the GT; any extra performance from the GTS comes from higher clock speeds. Both chips have 32 "stream processors" rather than the 128 or 96 of the two GeForce 8800 GPUs. Elsewhere, it's much the same, with setup engines and thread-dispatch units all scaled down to be proportional to the reduced bank of stream processors. While stream-processor complement is the only major change between the GeForce 8800s and the 8600s, there are more; see our online preview at www.pcpro.co.uk/news/110357 for details.

While the stream processors of the GTS run at an impressive 1.45GHz (faster than even those of the 8800 GTS), the GT stream processors run at a more reasonable 1.19GHz. The "core" (as Nvidia describes those subunits surrounding the processing pipelines) runs at 675MHz on the GTS and a still rapid 540MHz on the GT. To round things off, the 256MB of RAM of the GTS runs at a lightning-quick 1GHz, dropping to 700MHz on the GT.

The cards

The Gigabyte GV-NX86T256D keeps to Nvidia's script as far as clock speeds go, but ditches the active heatsink in favour of that stylish metal grille. And while you may feel tempted to skip to the GTS reviews, scores for this card are acceptably good, especially given the price. Using the settings outlined (below left), we saw 29fps in Call of Duty 2 (CoD2), 42fps in Far Cry and 21fps in Elder Scrolls IV: Oblivion. Dropping the AA and AF boosted scores to an even healthier 35fps in CoD2 and 44fps in Oblivion. At £73 (£86 inc VAT), and with a copy of the excellent Supreme Commander, it's an absolute bargain.

With the difference between GT and GTS being clock speed, the pre-overclocked XFX GeForce 8600 GT XXX Edition could be the bargain of the year. However, XFX charges a hefty premium for the overclock: the £98 (£115 inc VAT) gets you a "core" speed of 620MHz and a RAM speed of 800MHz. However, to really match the 8600 GTS you'd also have to overclock the stream processors, something that can only be done with a custom-written graphics-card BIOS, which no company managed for this test. The high price isn't quite justified by the performance, though, with scores up from the Gigabyte by between 2fps and 5fps. The highlights were 33fps in CoD2 even with our 4x AA and 8x AF applied, while Oblivion ran at a super-smooth 49fps when we removed the AA and AF. However, you get next to nothing in the box; only one DVI-to-D-SUB converter and a 4-pin video cable to the two converters, 7-pin cable and recently released game from Gigabyte. This card ultimately fails to justify its price tag.

The most disappointing of the 8600 GTS cards is the ECS N8600GTS-256MX+, but, again, only because of its price. The box is neat and minimises waste, but contains nothing beyond the usual video cable and two DVI-to-D-SUB converters. Meanwhile, the card itself has received some factory-based overclocking, pushing the "core" to 720MHz and the RAM to 1.1GHz. We saw frame rate boosts of up to 2fps across all the tests, but it still does nothing to justify the highest price on test.