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Sapphire Radeon HD 7950 OC Review

AMD’s reference HD 7950 board sets its core clock at 800MHz and memory at 1,250MHz, using the default cooling system. Sapphire takes this reference board, adds dual 12cm fans, and juices the core clock to 900MHz. The memory clock remains at 1,250MHz—but that’s 3GB of 1,250MHz GDDR5. Priced at around $480, it’s worth seeing how the card compares with Nvidia’s GTX 580. Note that we’ve also included results from the XFX Radeon HD 7970 for your reference, but excluded that card from the direct comparisons.

For direct comparison we turned to two different versions of the GTX 580—the slightly overclocked EVGA GTX 580 SC with 1.5GB of GDDR5 and the ultra-beefed-up EVGA GTX 580 Classified with 3GB of video RAM—as well as the XFX Radeon HD 7950 Black Edition reviewed next.

The Sapphire card ships with a slight memory bandwidth disadvantage compared with the XFX card (5GB per second versus 5.5GB/s) due to running its GDDR5 frame buffer at the reference clock speed. This shows up in a few benchmarks, where the Sapphire card places just a little behind the XFX card, but the differences are pretty small.

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XFX Radeon HD 7970 Black Edition Review

‘We don’t need no stinkin’ reference design!’ says XFX

It's not unusual to see factory-overclocked videocards ship with custom cooling solutions a few months after a GPU launches. But XFX didn’t waste any time with its Radeon HD 7970 Black Edition—a factory-overclocked card with a custom cooling solution that aims to take the performance crown. Based on what we’ve seen to date, XFX has delivered the fastest single-GPU card on the planet.

The Radeon HD 7970 is AMD’s latest GPU, with support for DirectX 11.1 and OpenCL 1.2. It’s a brand-new architecture—completely different from past AMD GPUs—built on TSMC’s 28nm manufacturing process and sporting a staggering 4.3 billion transistors. In AMD’s reference design, the 7970’s core runs at 925MHz, and its GDDR5 memory is clocked at 1,375MHz. XFX ups the ante significantly, pushing the core clock speed to a whopping 1GHz and running its 3GB of memory at 1,425MHz.

As you might imagine, the results are nothing short of amazing. We’re seeing genuine performance milestones here, including a 3DMark 11 performance score higher than 8,000 (for a single GPU), Far Cry 2 hitting 100fps at 2560x1600 with 4x AA, and Batman: Arkham City heading north of 50fps at the same resolution and AA settings. On top of that, the idle system power is just 124 watts, and a dark idle (when Windows 7 blanks the screen) draws 110 watts. Push the card and you’ll see system power consumption climb to 349 watts, but that merely puts its overall power draw into Fermi territory. XFX’s Radeon HD 7970 Black Edition is substantially faster than EVGA’s super-overclocked 3GB GeForce GTX 580 Classified, and it’s outfitted with just two PCIe power connectors (one 8-pin and one 6-pin). EVGA’s card requires three power connectors.

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Sapphire Radeon HD 6790 Review

Remember the Radeon HD 5830? That videocard filled a certain price point, but it was actually the same GPU used in the high-end HD 5870, with a large chunk of the die disabled. Enter the Radeon HD 6790. At first blush, it’s similar in concept to the HD 5830. AMD took its Barts GPU (used in the Radeon HD 6870 and 6850) and disabled a big chunk of it. Voilà: the Radeon HD 6790.