Radeon HD 5970: The Card In Detail
The Radeon HD 5970 is a truly massive graphics card, even for a high-end dual-GPU product. Its dimensions whale anything previously seen, measuring in at 30cm long and weighing a little over 1kg.
Our review sample hung a total of 6cm off the edge of our Asus P6T Deluxe motherboard used for testing.
Cooling the Hemlock XT GPUs is a large aluminum heatsink made up of 36 fins. Measuring 16cm long, 7cm wide, and 2.5cm tall, it is slightly larger than that used in the Radeon HD 5870. Connected to the base of this heatsink is a massive copper plate which helps improve efficiency, while a 75x20mm blower fan draws air in from within the case and pushes it out through the rear of the graphics card.
For the most part this fan operates very quietly, helped by the impressively low 42 watt idle consumption of the Radeon HD 5970. When gaming, the fan will inevitably spin up as the card can consume up to 294 watts under load, but even with the increased thermal stress the 5970 does not scream at intolerable levels.
The heatsink and fan have been enclosed within a custom built housing that conceals the entire graphics card, which is the same design used with the Radeon HD 5870. This setup helps protect the card very well; Nvidia has been using similar enclosures for some time with their most prized graphics cards, such as the GTX 295.
Removing the heatsink exposes the two GPUs, GDDR5 memory chips, and a few other critical components.
With the heatsink off the Radeon HD 5970 looks almost identical to the Radeon HD 4870 X2, though it is noticeably longer.
Key changes involve the new GDDR5 memory, improved power circuitry, and an updated 2.0 PEX bridge from PLX Technologies, used to link the GPUs together. All this hardware is cooled via the large heatsink that covers the majority of the card's 30cm long PCB.
GDDR5 memory works at an ever more impressive frequency (1.0GHz x 4) on this particular model, which features a total capacity of 2GB. The core configuration of the Radeon HD 5970 doubles everything in the 4870 X2 with 1600 (320x5) SPUs, 80 TAUs (Texture Address Units), and 32 ROPs (Rasterization Operator Units).
AMD's reference card came equipped with Hynix ICs (H5GQ1H24AFR-T2C parts). These GDDR5 modules are rated for 1.25GHz operation, so we expect to push them beyond the stock 1.0GHz configuration without hassle.
In order to feed the graphics card enough power, a pair of PCI Express power connectors are used (6-pin and 8-pin sockets). This is the same configuration used by previous dual-GPU graphics cards such as the GeForce 9800 GX2 and Radeon HD 4870 X2, so current high-end power supplies should cater for this new graphics card.
The Radeon HD 5970 naturally supports CrossfireX technology, and therefore in the standard position we find a single connector for bridging two cards together.
The only other connectors can be found on the I/O panel. Our sample featured two dual-DVI connectors and a Mini Display Port connection. Just like the Radeon HD 5870, the 5970 can support a maximum resolution of 2560x1600 on not one but rather three monitors.