Here's a look at the different R600 versions:
So, the T-bone is full a 12 inches long (30cm). This baby is dubbed XTX, and will feature-top-of-the-line, 1GB GDDR-4 memory from Samsung. You can count on 16 memory chips yielding 1GB of video memory connected to the GPU via 512-bit external bus. Memory chips could do 2.4GHz clock (1.2GHz physical), yielding in yet unseen bandwidth of 153.6 GB/s, dwarfing 8800GTX and its 86.4 GB/s. However, this clock is not guaranteed - not everything is in the bandwidth, but rather in the way you use it.More details at The Inq. The launch of these cards is expected in March, close to the start of CeBIT in Germany.
Second variant is in the prime rib category more compact its big T-bone brother, on a size level with R580 (X1950XTX) and G80GTS (8800GTS) boards. We're talking about "X2x00 XT", which is pretty much the same thing as XTX, featuring only a speed downgrade. The speed downgrade enabled DAAMIT to put a more compact PCB, nine inches in length but still featuring the same amount of GDDR-4 memory. Depending on the price and availability of GDDR-4, this one will be available in 512MB variant as well. You know, X1900XT 512/256MB, only one GPU generation ahead.
The third one, let's call it sirloin steak, is sort of X1800XL style ("X2x00XL"). We're talking about still GDDR-4 memory, but a new 9-inch PCB. Nope, this is not a downgraded PCB from the already-mentioned XT part, we're talking about a board which will feature "normal" clocks and be available for OEMs to do wonderous display output things with. Multimedia addicts will be happy with the whole array of possibilities, thanks to the fact that ATI killed its decade old ViVo chip. Single-slot ahoy.
Fourth class, mignon filet, is dubbed X2000GT, and this is a product which will feature most of the non-100% QA chips around. The PCB is once again new and does not derive from above mentioned three models - but still inside the 9 inches of length (three different 9-inch versions, guys really like the number). This baby was codenamed UFO, and had a very difficult birth: it was introduced, then shafted, then re-introduced into the pipe again – and this is the R600 chip combined with cheap and massively available GDDR-3 memory. This will be the ground for GPGPU boards as well, since AMD plans for both 1GB and 2GB versions of the boards. 2GB versions are of course, reserved for the high-end, professional market.