AMD will on March 31st launch the new mid-range card Radeon HD 6790. After we recently revealed the launch date we now have the specifications that turned out to be similar to those of the Radeon HD 6800 family, since the card is based on a GPU from the Barts series.
UPDATE: We just learned that AMD has postponed the launch to the 5th of April, probably to give AIB’s more time to get their cards ready for the market. We will have more information on this and the power usage issue later today.
AMD Radeon HD 6790 will use a graphics circuit called Barts LE and as we implied in our initial article on the new card the similarities with the more powerful Radeon HD 6800 series are quite striking.
Barts LE uses AMD’s classic VLIW5 architecture and will get 10 SM units (Streaming Multiprocessor) with access to a total of 800 stream processors. This can be compared to 12 SM units and 960 stream processors in Radeon HD 6850 that is based on Barts Pro.
Radeon HD 6790 has beside fewer processing units the same bus width at 256-bit and relatively powerful clock frequencies. The GPU operates at 840 MHz while the memory shuffles data at 1050 MHz (4200 MHz effectively). All to put NVIDIA’s newcomer GeForce GTX 550 Ti in its place and offer a more powerful alternative to Radeon HD 5770, at a lower price than Radeon HD 6850.
| HD 6790 | HD 6850 | HD 6870 | |
| GPU | Barts LE | Barts Pro | Barts XT |
| Node | 40nm | 40nm | 40nm |
| Die size |
255 mm2 | 255 mm2 | 255 mm2 |
| Transistors | 1.7 Billion | 1.7 Billion | 1.7 Billion |
| SM units | 10 |
12 | 14 |
| Stream processors | 800 |
960 | 1120 |
| GPU frequency |
840 MHz | 775 MHz | 900 MHz |
| Performance | 1.34 TFLOPs | 1.5 TFLOPs | 2.0 TFLOPs |
| Texture units |
40 | 48 | 56 |
| Texture fillrate | 33.6 Gtexel/s | 37.2 Gtexel/s | 50.4 Gtexel/s |
| ROPs | 32 |
32 | 32 |
| Memory type |
GDDR5 | GDDR5 | GDDR5 |
| Memory buffer |
1GB | 1GB | 1GB |
| Memory frequency |
1050 MHz (4200MHz) |
1000 MHz (4000MHz) |
1050 MHz (4200MHz) |
| Bus width |
256-bit | 256-bit | 256-bit |
| Bandwidth | 134.4 GB/s | 128 GB/s | 134.4 GB/s |
| Power connectors |
2 x 6-pin | 1 x 6-pin | 2 x 6-pin |
| Power consumption |
19/150W | 19/129W | 19/151W |
NVIDIA chose to launch a relatively crippled card in a higher product series, GeForce GTX 550 Ti, which runs the risk of confusing the consumers. AMD has done the opposite. Radeon HD 6790 is with the Barts LE GPU a toned down version of Radeon HD 6850 and could very well have been named Radeon HD 6830. Instead AMD chooses to lift the card into the Radeon HD 6700 series.
Radeon HD 6790 – Worse performance at higher power consumption?
The last piece of the specification is a bit confusing. Radeon HD 6790 is expected to perform worse than Radeon HD 6850, but still consume more power. AMD has specified the power consumption to maximal 150 watt, which can be compared to 129 watt for Radeon HD 6850 or 151 watt for Radeon HD 6870. With relatively high GPU and memory frequencies this sounds a lot like the launch of Radeon HD 5830 where AMD managed to launch a card that despite worse performance consumed more power than the faster brother.
Considering GeForce GTX 550 Ti is rated at 116 watt we can’t really find a way to justify how Radeon HD 6790 can consume 150 watt, but this is what our sources are telling us. On March 31st we will know exactly what the number will be, but AMD has not developed a new GPU for Radeon HD 6000 but instead uses the well established Barts architecture.
