Shortly after the launch date for AMD Radeon HD 6990 graphics card was set, we have found that, almost a full set of presentation slides for that dual-GPU beast leaked on Internet. Therefore, it is time to lift the veil of secrecy over specification details as well as AMD’s performance numbers.
Introducing the AMD Radeon HD 6990, codename Antilles. This card is based on two Cayman XT GPUs that are produced by 40nm process technology. The same graphics processors is used in AMD’s top single-GPU solution — HD 6970 — with 1536 Stream processors and 2GB of GDDR5 memory running trough a 256-bit interface. Important to note, performance configuration for each GPU og Radeon HD 6990 has not been cut compared to HD 6970, except for clocks. So, by simply doubling the specs, we get 3072 SPs, 192 TMUs, 64 ROPs and total of 4GB of vRam via 2×256 bit bus. As for clocks, the numbers are, 830MHz for GPU and 1250MHz (5000MHz QDR) for memory.
Next, we can spot the same Dual-BIOS switch that was first introduced by AMD in single-chip Radeon HD 6900 line-up cards. As you might remember, Dual-BIOS technology in Radeon HD 6950/6970 allowed user to flash the card with custom made firmware in order to reach the desired performance result ( 1st position of the switch) and in case of failure, there was always an opportunity to return to default settings (2nd position of the switch). However, for HD 6990 this works a bit different: position 1 now brings overclocked settings for HD 6990 (HD 6990 OC), increased GPU clocks (880MHz) and voltages (1.175V). These settings are dedicated mostly for hardware enthusiast and overclocks. The 2nd postilion of the BIOS switch rolls the settings back to stock, 830MHz and 1.12 V respectively.
Though BIOS-switching does no effect memory clocks, overclockers can reach up-to 6000MHz rate by tuning AMD Overdrive features in Catalyst Control Center. Same can be done to reach even higher (900MHz +) GPU clocks due to loose overclocking limits. But don’t forget, that all these manipulations require additional power and cooling.
Speaking of power, PCB of the novelty has a symmetrical design with VDDC regulators, made by Voltera, located in the center of the card thus proving efficient power delivery for each GPU and its associated memory. At the same time, these premium-quality chips ensure high efficiency and low leakage. Though AMD indicates regulators to draw less power, it was hard for Radeon HD 6990 to stay within 300W TDP limit considering it holds two full-fledged Cayman XT chips. With that said, typical gaming power for default clocked HD 6990 is 350W.
This became possible thanks to use of AMD PowerTune technology that allows safe performance tuning for boards consuming more that 300W, providing smooth game application handling in return. The maximum for PowerTune is only 25W higher, 375W. As for HD 6990 OC variant, the numbers are 415W and 450W! respectively, leaving enough room for a descent overclock. Just imagine the potential of this card with PowerTune disabled.
It is good to know AMD cares about overclocks too, as the cooling systems is designed to handle that much of heat generated. In details, dual-slot cooler includes two vapor chambers with one fan located in the center and providing 20% more airflow compared to previous ATI/AMD dual-GPU flagship, HD 5970. The back of the card is fully covered with addition heat spreading plate. The PCI-bracket features perforated area for blowing out the hot air while beneath it there are display connectors, lined in a single row, that are optimized for AMD Eyefinty technology.
According to AMD’s internal performance results the novelty is said to beat NVIDIA’s current flagship, GeForce GTX 580 by 67% on average. The factory overclocking should bring a minor in-game FPS boost, 4% on average. On the other hand, Radeon HD 6990 demonstrates awesome CrosfireX performance scaling, with numbers reaching almost doubled results compared to a single card. Are these figures trustworthy or not we will find out next week on 8th of March, when the card will be officially presented.