AMD was forced to delay its coming flagship Radeon HD 6990 to next year, but the card that sports dual Cayman GPUs and is expected to bring back the performance throne has now shown its specifications, where a theoretic performance of 6 TFLOPS is one of the goodies.
AMD Radeon HD 6990 will launch sometime in Q1 2011. It will bear two powerful Cayman XT graphics circuits and if the picture that has been published is genuine each Cayman XT GPU will house 1920 stream processors, a number that has been circulating for some time.
This would result in Radeon HD 6990 having 3840 stream processors, a pretty staggering number that is backed up by just as staggering performance of 6 TFLOPS at single precision. At double dubbel precision the power will be 1.5 TFLOPS.
If we look at the raster performance AMD has made even more improvements here. By allowing 2 polygones per clock cycle, double from Cypress, Radeon HD 6990 can push out 64 pixels per clock and reach a theoretic raster performace of 3100 Mtri/s, which more than double of Radeon HD 5970 that reaches 1450 Mtri/s.
With 4GB GDDR5 graphics memory Radeon HD 6990 is a real beast, something that also shows in the power consumption. Without load it will stay at 30 watt, but fully loaded the card goes nuts and can drain up to 300 watt. Though, the precursor HD 5970 was also capable of this.
| Radeon HD 6990 | Radeon HD 5970 | Radeon HD 5870 | |
| GPU | 2 x Cayman XT |
2 x Cypress | Cypress |
| Node | 40nm | 40nm | 40nm |
| Stream processors | 3840 |
3200 | 1600 |
| Performance | 6.0 TFLOPS | 4.64 TFLOPS | 2.72 TFLOPS |
| Geometric perf. |
3 100 Mtri/s |
1 450 Mtri/s | 850 Mtri/s |
| Graphics buffer |
4GB GDDR5 |
2GB GDDR5 | 1GB GDDR5 |
| Memory interface |
2 x 256-bit | 2 x 256-bit | 256-bit |
| Memory bandwidth |
307,2 GB/s | 256,0 GB/s | 153,6 GB/s |
| Power consumption |
300W/30W | 294W | 188W |
If these numbers are correct – which we cannot confirm – AMD has managed to make its shader architecture more efficient, when moving from 5D to 4D clusters. Even if the number of stream processors aren’t that many more we can expect a significant increase in performance through a more efficient use of the stream processors and a lot better raster performance. In three weeks Cayman is expected to find the market in the form of Radeon HD 6970 and Radeon HD 6950, cards we really look forward to testing.
