Details of Radeon HD 4870 X2 aka R700/Spartan
Only a few days in advance of the alleged release date (July 14th - date not confirmed yet) Tom's Hardware published two transparencies with details of the HD 4870 X2.
In addition to the already know details, like 2 GiByte GDDR5 VRAM and 2x 800 stream processors, there are interesting things to be read. The memory transfer rate is given with 230 GiB/sec. - exactly twice the size of the HD 4870. Therefore the clock speed of the memory has to be as high as with the HD 4870: 900/1,800 MHz. Furthermore the HD 4870 X2 is said to have an energy efficiency of 8.8 FLOPS per Watt - the also given performance of 2.4 TFLOPS would therefore indicate a power consumption of 272 Watt.
There also is a 3DMark Vantage result of 6,920 points in the Extreme preset (we tested the Geforce GTX 280 with about 4,800 points). It is also said, that not all of the HD 4800 products have support all the Powerplay features, which is worrying so let's hope this refers to the mobile versions only.
Grafikkarten-Rangliste 2016: 32 Radeon- und Geforce-GPUs im Benchmarkvergleich [Oktober]