Nvidia’s new cards are called the GeForce GTX 260 and GeForce GTX 280 – confusing names, since GTX has previously always been a suffix. Both are based on the GT200 core, a new GPU built with the same 65nm process as existing GeForce 9000 series cards.
The GTX 280 offers 240 stream processors with a core clock speed of 602MHz, while the GTX 260 has only 192 stream processors and a slightly slower clock speed of 576MHz. These strange numbers seem to be a hallmark of the new cards: the GTX 260 comes with 896MB of GDDR3 clocked at 999MHz, while the 280 offers
a full gigabyte at 1107MHz.
The 260 also uses a novel seven-channel memory controller, giving it a bus width of 448 bits and an effective memory bandwidth of 112GB/sec. The 280 raises this to a full 512 bits for a bandwidth of 142GB/sec.
Some of these design decisions may seem arbitrary, but you can’t argue with the results. In our high-detail Crysis benchmarks, for example, the GeForce GTX 280 averaged a phenomenal 45 frames per second. That’s a 25% improvement over Nvidia’s previous flagship, the GeForce 9800 GTX.
Even with the detail settings turned up to very high, and resolution pushed all the way up to 1900 x 1200, the GTX 280 still managed a just-about-playable 23 frames per second in Crysis. The GTX 260 didn’t disgrace itself either, though at 39 frames per second at high detail it wasn’t usefully faster than a
The new cards showed their strength in Call of Juarez too. The mighty GTX 280 showed a remarkable 76% improvement over its predecessor at high detail, and even the GTX 260 was 43% faster than the 9800 GTX.
These are exciting results; but there’s a catch. The new GT200 core that is behind these great strides forward in performance is a huge beast, comprising 1.4 billion transistors in a massive 575mm2 die – the largest single GPU ever made.
This makes the new cards expensive. The GTX 260 comes in on decidedly the wrong side of $350, while the GTX 280 currently sells for an eye-watering $554. These prices effectively put Nvidia’s new cards out of reach to all but serious gamers.
ATI Radeon HD 4000 Series
ATI, meanwhile, has been working on its own secret weapons: the Radeon HD 4850 and 4870. The cards were audaciously rolled out just a fortnight after Nvidia’s new GTX cards, but they come from a very different school of design. While Nvidia’s evident goal has been to maximise raw power at any cost, ATI
has focused on efficiency.
ATI’s new RV770 core uses under a billion transistors, and is built on a 55nm process, as against the GT200’s 65nm fabrication. This keeps its area to just 260mm2 and leads to far lower prices than Nvidia’s monsters. At the time of writing, Gigabyte Radeon HD 4850 and HIS HD 4870 cards were available online
for $229 and $349 respectively. Power consumption is lower too: the HD 4000’s quoted maximum power drain is 160W, against 240W for the new GTX cards.
But capabilities haven’t been squeezed in the process. Both cards feature a remarkable 800 stream processors – more than three times as many as the GTX 280. Coupled with higher core speeds than the GTX cards (625MHz and 750MHz respectively for the HD 4850 and HD 4870), this enables both cards to exceed 1
teraflops (1012 floating point operations per second). The HD 4870 also benefits from ATI’s use of 900MHz GDDR5 RAM, enabling it to achieve a memory bandwidth of 115GB/sec – more than the 260 GTX – despite using only a 256-bit memory bus.
The HD 4850 uses 993MHz GDDR3 over the same bus, reducing its bandwidth to 64GB/sec. At present both cards ship with 512MB, but a 256MB HD 4850 is planned, along with a 1GB HD 4870.
Despite these technical advances, it was no real surprise that the $349 HD 4870 couldn’t best the $554 GTX 280 in our Crysis benchmarks. Nevertheless, its score of 39 frames per second at high detail was extremely creditable, rivalling the 260 GTX. The HD 4850’s 32 frames per second was lower than the 9800 GTX’s 36, but still made the game very playable at high settings – an achievement that would have been unthinkable for a card of this price not too long ago.
What’s more, in the Call of Juarez test, the HD 4870 pipped the GTX 280 to the post, attaining the highest score we’ve yet seen, and the HD 4850 pulled almost level with the GTX 260. It’s clear that the HD 4000 series’ massively parallel architecture has immense potential – as long as game designers take
advantage of it.
Which card you choose – Nvidia or ATI – is a simple question of balance. If you demand the very best performance, the GTX 280’s all-round appeal is untouchable. But while die-hard gamers may be able to justify the huge asking price, most will be looking for the bang-per-buck sweet spot – and today it lies unarguably with ATI. The HD 4870 delivers the power of a GTX 260 for $17 less, while the HD 4850 makes modern games fly at a price that’s simply incredible.
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