AMD Radeon HD 6970 review

Graphics card manufacturers usually release the high-end versions of a new architecture first, and then scale down the design to provide more affordable versions of the graphics card. AMD, having now discarded the ATI brand, has taken a different strategy with its 6000-series.

We saw the mid-range 6800 cards a couple of months back, such as the Radeon HD 6870, and now we have the more enthusiast-orientated 6900 pairing – consisting of the HD 6970 and 6950 predictably. Both are actually based on a different architecture from their little siblings.

The cards’ Cayman graphics core has the same 40nm fabrication process as the Barts core in 6800 cards, and the whole 5000 series. It’s not the major step forward then that we’d hoped for, but it’s still an impressive chip, the biggest AMD have ever made, with 2,640 million transistors, up from 2,154 from the previous generation.

There are still plenty of interesting revisions in the design. Dual graphics engines are one innovation, so it can handle greater quantities of geometry and has two tessellation engines – DirectX 11 supports tessellation to add more detail into scenes. AMD claim they have increased tessellation performance by up to three times over their previous architecture.

The HD 6970 has a massive 1,536 stream processors, which support new image quality features. The key one of these is Enhanced Quality Anti-Aliasing (EQAA), which takes extra samples from a scene during anti-aliasing for almost no performance hit. The extra samples increase accuracy and so improve edge smoothing, it’s only really noticeable at low resolutions and low anti-aliasing settings – which aren’t why you buy a high-end card like this.

There’s 2GB of GDDR5 fitted, the most amount of memory we’ve ever seen on a single-core graphics card. It’s running at a swift 1,375MHz, and the card uses a 256-bit memory bus – so no bottlenecks here.

The HD 6970’s core runs at 880MHz, the fastest core speed the company has ever used. Or at least it does the vast majority of the time. AMD’s new PowerTune technology allows the company to reign in the ever-escalating power demands of graphics cards without impacting on day-to-day performance. Sensors in the card measure power draw at every clock cycle, and dynamically scale the core speed to keep it within the 250W TDP. This allows for a high base core speed, which is then throttled only under extreme cases – such as testing utilities that are designed to hammer the hardware. We never saw the clock scale back on our test samples during our various tests. You can adjust the degree to which PowerTune curbs performance in the Catalyst Control Centre, allowing users to increase the cards maximum TDP if they feel it necessary.

All that power is drawn through two connectors, one 8-pin and one 6-pin. Make sure your power supply has the necessary connectors and can handle the 250W draw before buying. The card itself is slightly larger than the 6800 series models, measuring 275mm in length, but it should still fit fine in most PC cases. There are the usual PCI-Express and CrossFire connectors, but what’s new is the small switch by the latter. This gives you access to dual BIOS, so you can make updates to the card without risking the original settings.

Display outputs haven’t changed from the 6800 series. There’s still two DVI connectors, only one of which can handle Dual-Link for display resolutions over 1,920×1,080 at 60Hz. A single HDMI 1.4a port provides full support for 3D viewing, along with output of HD audio from Blu-ray movies, such as DTS Master Audio. Finally, there’s a pair of mini DisplayPort 1.2 outputs, which enable numerous multi-monitor setups using AMD’s Eyefinity technology.

With all that covered, let’s get down to some performance figures. The HD 6970 is a very quick card, scoring highly in all our tests. Testing at a Full HD resolution with 4x anti-aliasing and Very High detail, it scored 41.9fps in our Crysis test, almost exactly the same as the GTX 580 with 41.0fps.

In our DirectX 11 Stalker test, the HD 6970 placed just ahead of the GTX 580, with 56.3fps compared to 54.7fps. However, in the newly released 3DMark 11 – run at our own custom settings of Performance preset, 1,920 x 1,080, 4x anti-aliasing and 8x anisotropic filtering – the situations were reversed, with the GTX 580 scoring 1,985, to the HD 5970’s 1,854.

Being available for a surprisingly low £290 inc VAT, the HD 6970 is a better buy than Nvidia’s GTX 580 at a wallet-busting £380. Even so, it’s a lot to pay for a graphics card, especially when you can get very similar performance from its little sibling, the AMD Radeon HD 6950 for around £70 less.

For the purposes of this review, we were supplied with prices by card manufacturer HIS from www.overclockers.co.uk. Prices are likely to be volatile, however, with potentially-limited availability pushing prices higher. If you’re keen then we’d recommend getting in quick.