GeForce GTX 280 review - 4 - Meet the twins

GeForce GTX 260 & 280

Okay then people, it's time to get a little deeper under the hood and inside that thing we like to call the GPU. As you noticed, NVIDIA is actually releasing two products today.

• GeForce GTX 280: 602MHz GPU, 240 shaders, 1296MHz shader processors, 1107MHz memory, 1GB memory, 512-bit memory bus, 141.7GB/s memory bandwidth, 48.2 billion/s texture fill rate
• GeForce GTX 260: 576MHz, 192 shaders, 1242MHz shader processors, 999MHz memory, 896MB memory, 448-bit memory bus, 111.9GB/s memory bandwidth, 36.9 billion/sec texture fill rate.

GeForce GTX 260

The cheaper GeForce GTX 260 will be priced at an interesting $399 and inevitably will fight with ATI's upcoming Radeon RV770/4870. The GeForce GTX 280 will be about 25 per cent faster than the 260, yet cost more with a steep $649 sales price.

The new GTX GPUs embed new technology but for the end-user nothing really changed other than raw performance and power management. The features are 98% similar to the last gen-products, which also means the lack of DirectX 10.1, though not that important I do wish it would have been implemented. Especially in this price-range.

GeForce GTX 280

The GeForce GTX 280 has a pretty amazing 240 stream processors and runs at a core clock frequency of 602MHz. There are more clocked domains inside that GPU though, the shader processor run at 1296MHz and the memory is at 1107MHz (effective 2214 MHz). All-in-all we feel the clocks are a little bit on the conservative side.

This high-end part has 1GB of GDDR3 memory which has a 512-bit memory bus that binds to 8 memory controllers inside the GPU. At the end of the pipeline we run into an improved ROP (Raster Operation) engine, and the 280 has 30 of them.

All that brute transistor power results into roughly 933 GFLOPS of performance (depending how you measure actually), so with the clocks as they are .. NVIDIA missed the Teraflop by a very small margin.

A tad unexpected is to see that this card needs both a 6-pin and 8-pin power connector to get enough juice. NVIDIA claims a TDP (peak wattage) of roughly 235 Watts, which in all honesty is not even that bad considering the GeForce 8800 Ultra isn't that far off from that number either. And trust me when I say .. this puppy is roughly twice as fast.

But there's more than the GTX 280 been released today. When we peek at the GTX 280's little brother, the GTX 260, we see a very similar product yet with some distinct changes that will lower performance by a factor of 25'ish percent. The GeForce  GTX 260 is in fact the same silicon yet with with 192 shader processors and 896MB GDDR3. This sums up to 192/8 = 24 ROPs at the end of the pipeline.

The clock frequencies for the GTX 260 are 576MHz GPU, 999MHz memory and 896MHz GDDR3. On a 448-bit memory interface. Why this weird number you ask? It has everything to do with the way the architecture is arranged. Each memory controller in the GPU accumulates the memory bus width.

So the GTX 280 has eight 64-bit memory controllers, 8x 64-bit = 512 Bit.

Then if the GTX 260 has a 448-bit interface, you can divide by 64-bit, and now we can easily see that the 260 is missing one memory controller opposed to daddy GTX 280, thus 7 active memory controllers.

The power for the GTX 260 is fed by two six-pin connectors. Power consumption for this 10.5-inch board is 182W.