Nvidia GeForce GTX 680 review

£430
Price when reviewed

AMD was first out of the gates with 28nm, but every Radeon HD 7000 Series card we’ve so far reviewed has come with a big caveat: wait and see what Nvidia does. Now the first 28nm “Kepler” chip is in our Labs, we can safely say we hope you heeded that advice – Kepler was worth the wait.

The GeForce GTX 680 is Nvidia’s new single-core flagship card, tweaked, refined and renamed from the “Fermi” architecture first launched with the GTX 480 in 2010. Graphics Processing Clusters, or GPCs, still form the building blocks of the new GPU, with each having its own resources for shaders, textures and compute processing. Each pair of GPCs shares a memory controller, but L2 cache is shared between all of the card’s GPCs.

While the GTX 480 and GTX 580 made do with 15 and then 16 GPCs, each with 32 stream processors, Nvidia is using only eight clusters on the GTX 680, each boasting 192 stream processors. That’s a huge increase, and closer to the 2,048 stream processors AMD includes in its flagship Radeon HD 7970.

Nvidia GeForce GTX 680

Nvidia’s biggest new feature is something you won’t find on any AMD card: GPU Boost. With a nod to Intel’s Turbo Boost, it dynamically adjusts the core clock from the stock 1,006MHz depending on the operating conditions – ours idled at 549MHz, for example. When performance is required it adjusts the core every millisecond to try to hit the 195W power draw ceiling – ours rose to 1,097MHz. Nvidia claims this constant power draw makes for a more reliable card, as it’s fluctuations in draw, rather than a high level, that harm reliability.

The card has 2GB of GDDR5 memory running at 6,008MHz – almost twice the speed of the Radeon HD 7970 – but the 256-bit memory bus is narrower. The transistor count of 3.5 billion is slightly less than the 4.3 billion on the AMD card, but the GTX 680’s texture fillrate of 128.8GT/sec is higher than the 118.4GT/sec of the HD 7970.

Nvidia GeForce GTX 680

That strength translates to strong benchmark results. In Crysis at 1,920 x 1,080 and Very High settings the GTX 680 averaged 70fps, 2fps ahead of the HD 7970. Both cards returned the same result at 2,560 x 1,600 – a playable 42fps.

The GTX 680 smashed the AMD card in Crysis 2. At 1,920 x 1,080 and Ultra settings – the toughest the game offers – it averaged 57fps, with the HD 7970 on 36fps. There was a sizeable gap when we upped the resolution, too, with the scores at 33fps and 26fps.

In Just Cause 2 at 2,560 x 1,600, the GTX 680’s 116fps was far better than the 70fps of the HD 7970. Our final games test, DiRT 3, saw similar gaps: at 2,560 x 1,600 the GTX 680 scored 75fps to the HD 7970’s 55fps.

Theoretical tests also highlighted the power on offer. In the TessMark tessellation benchmark the GTX 680 ran at 288fps, with the HD 7970 trailing at 79fps. In ShaderToyMark, designed to test shader performance, its 26fps bettered the AMD’s 18fps. And the GTX 680’s overall score of X2744 in 3DMark 11 beats the HD 7970’s X2720.

Nvidia GeForce GTX 680

All these speed advantages are achieved while also being more efficient. With the GTX 680 installed, our Core i7-3960X test rig hit a stress-test peak of 303W; lower than the 339W with the HD 7970 plugged in. A peak temperature of 81°C is nothing to worry about, and that figure will fluctuate depending on the coolers installed on partner cards.

Finally, a 257mm length means it won’t trouble decent-sized enclosures, and it takes two six-pin power plugs rather than the eight-pin plugs used on AMD’s high-end cards.

Nvidia GeForce GTX 680

With all this benchmark success, you might expect Nvidia’s new monster to be far more expensive than its AMD rival, but that isn’t the case. The GTX 680 has an SRP of £430 but you’ll likely be able to get hold of the card for less, while the cheapest HD 7970 cards have trickled down to around £400 since launch. Given the results we’ve seen it would need a price drop on AMD’s part to make it an even contest.

Until that happens, the high-end graphics card buying decision is a no-brainer. The GTX 680 is far quicker than the HD 7970 in the majority of our tests, and manages to be more efficient at the same time. Nvidia kept us waiting for Kepler, but now that it’s here you needn’t look anywhere else.

Core Specifications

Graphics card interface PCI Express 3.0
Cooling type Active
Graphics chipset Nvidia GeForce GTX 680
Core GPU frequency 1,006MHz
RAM capacity 2.00GB
Memory type GDDR5

Standards and compatibility

DirectX version support 11.0
Shader model support 5.0

Connectors

DVI-I outputs 2
DVI-D outputs 0
VGA (D-SUB) outputs 0
S-Video outputs 0
HDMI outputs 1
7-pin TV outputs 0
Graphics card power connectors 2 x 6-pin

Benchmarks

3D performance (crysis) low settings 189fps
3D performance (crysis), medium settings 118fps
3D performance (crysis) high settings 94fps

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