ATI Radeon HD 5970 Closer Look

During the 2009 business year we've seen dozens of great video games released on the PC platform, but very few of them demand any more graphical processing power than games demanded back in 2006. Video cards certainly got bigger and faster, but video games has lacked fresh development. DirectX 10 helped the industry, but every step forward received two steps back because of the Windows Vista O/S. Introduced with Windows 7 (and also now available on Windows Vista with an update), enthusiasts now have DirectX 11 detail and special effects in their video games.

DirectX 11 is that software development leap we've been waiting for. Screen Space Ambient Occlusion (SSAO) is given emphasis in DX11, allowing some of the most detailed computer textures gamers have ever seen. Realistic cracks in mud with definable depth and splintered tree bark make the game more realistic, but they also make new demands on the graphics hardware. ATI offers the Radeon HD 5970 Hemlock video card for enthusiast gamers wanting nothing but the best graphics experience.

The ATI Radeon HD 5970 is one of the longest graphics cards ever produced by AMD, measuring 12.1" long from end to end. This profile relegates the HD5970 to full-size ATX cases with plenty of breathing room. ATI produces and directly supplies every Radeon HD 5970 that operates at reference specification, with add-in card/add-in board partner artwork applied wherever necessary.

In terms of overall design, the Radeon HD5970 looks like a stretched version of the HD5870 or HD5850. The biggest difference between the Radeon 5970 and the 5800 series is the lacking native HDMI 1.3 port, and the replacement of a DisplayPort-A connection for the smaller DisplayPort-B input. Two DVI digital video outputs are connected to monitors for dual-view, or a third monitor can be added via DisplayPort to enable ATI Eyefinity technology.

Unlike the other cards in the Radeon HD 5000-series, namely the HD5850/5870, the Hemlock HD5970 exhausts the heated air outside of the computer case. This is critically important, considering that the reference-speed Radeon HD 5970 we received for testing often passed 90°C in a 20°C room. The heated air coming out of the graphics card was hot, but nothing compared to the backside of the Radeon HD 5970. The 'Hemlock' graphics card pairs two Cypress-XT GPUs, and under load the retention brackets were measured to exceed 80°C - enough to scorch the hand that touches it.

The exposed view below illustrates the compact layout of electronic components which build the Radeon HD 5970. ATI intentionally reduced the clock speeds of the two Cypress-XT GPUs and GDDR5 vRAM to reduce TDP to under 300 watts at full load. ATI's uses the revamped PLX ExpressLane CrossFire bridge (good for 96-lanes of PCI-Express 2.1 bandwidth), which enables a new feature they call 'CrossFire Ultra-low Power State'. This new feature shuts down one of the GPU's and places it into a suspend power state when the video card doesn't require the graphics processing power. The end-result is an extremely efficient graphics card at idle.

Although designed for under 300W, the 6+8-pin power connections are good for up to 400W on demand and the cooling unit also offers more thermal control than necessary. AMD uses digital programmable Volterra regulators, Japanese pure ceramic SuperCapacitors, and 5.0 Gbps rated Qimonda GDDR5 to allow additional overclocking headroom. Doing this has enabled ATI to offer a quasi-Black Edition video card so that overclockers can have their way with it. ATI in-house tests pushed a Radeon HD 5970 up to 970MHz on each GPU, but individual results will vary depending on manufacturer and chip binning.

Considering the Cypress-XT GPU die size is a rather large 334 mm2, and fits 2154 million transistors, the overall heat dissipation is spread over a suitable landscape. The double-height cooler does a very good job of cooling two GPUs, but there is still a tremendous amount of heat that builds up on backside of the PCB. If you plan to overclock, I recommend that special attention be paid to the alloy plate mounted to the backside of the PCB of this video card.

In next several sections, Benchmark Reviews details our methodology for testing video cards followed by a performance comparison against many of the most popular graphics accelerators available. The Sapphire ATI Radeon HD 5970 competes against the dual-GT200 GPU NVIDIA GeForce GTX 295, so of course we'll be keeping a close eye on comparative performance.

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