Nvidia GeForce GTX 680

The tennis game-style back-and-forth exchanges between AMD and Nvidia in their struggle for video card supremacy are enough to bewilder even the most dedicated enthusiast. Generation after generation, each company seems devoted to making changes just big enough to surpass the other?until next year, at any rate. Though at first glance it appears that Nvidia is continuing the trend with its release of its new GeForce GTX 680 video card ($499 list), based on its new Kepler architecture, there are some surprises hidden deeper. Nvidia has delivered fine frame rates, but forgone domineering supremacy of them to tackle design and power usage in ways neither company has in years. That makes the GTX 680 a card that looks thrillingly forward, even if it doesn?t always advance the performance discussion by leaps and bounds.

Kepler builds on the Fermi architecture Nvidia introduced in 2010, when it released its GeForce GTX 480. It utilizes a new version of the Fermi SM (or Streaming Multiprocessor) called SMX, which performs most of the calculations needed to render the graphics. There are two SMX units per Graphics Processing Cluster (GPC) and four GPCs on the GTX 680?s 28nm GPU?in other words, this is a fully loaded video card. It boasts a total of 1,536 CUDA parallel processing cores, 128 texture units, and 32 ROP units. Its 2GB of GDDR5 memory runs over a 256-bit memory interface (with four 64-bit controllers).

The GTX 680 has a base clock speed of 1,006MHz, but that?s only part of the story. A new technology called GPU Boost, which is similar to the Turbo Boost and Turbo Core technologies Intel and AMD have implemented in their recent processors, can dynamically crank up the clock to an average of 1,058MHz, provided it?s still operating within the proper power window?but if it can go higher, it will. (Nvidia claims it has seen speeds upwards of 1.1GHz.) The card?s TDP is a nontrivial 195 watts, and Nvidia recommends a 550-watt power supply at the minimum?all of this should tell you this is a card that takes its power seriously. (We?ll investigate this further in a while.)

One thing hasn?t changed from previous cards: Though Nvidia claims it has redesigned the fan on the GTX 680 to reduce noise and the heat sink to improve efficiency and airflow, it still uses a huge combo unit that will block an adjacent expansion slot, so plan appropriately when you?re installing. The GTX 680?s ports may not look surprising (two dual-link DVI, one HDMI, one DisplayPort), but they can do something previous Nvidia cards have not: drive four monitors at once without requiring a second card. Three of these can even be configured to use 3D Vision Surround, Nvidia?s multimonitor stereoscopic 3D technology, and the fourth can be employed for more (sigh) useful purposes.

Two other design advancements are more noticeable to the naked eye. First is that the company has taken one big (and good) step backward by reducing the length of the card. The GTX 680 measures just over 10 inches in length, which is unusual given that 11-inch flagship cards are the norm. Its auxiliary power connectors are also not what you?ve come to expect: Rather than one eight- and one six-pin PCI Express (PCIe) connector, it uses two six-pin connectors. Even more surprising is that they?re stacked, rotated 180 degrees with respect to each other, along the width of the card rather than its length. This orientation reduced clutter in our test system somewhat, but it made our PCIe power plugs a bit more difficult to remove; this is an interesting idea that we?re not yet totally sold on.

Of course, what really counts with a video card is its performance, and there the GTX 680 doesn?t disappoint. It turned in the highest single-GPU results we?ve seen on a number of our tests, when compared with the previous champ, the AMD Radeon HD 7970: a score of 3,151 in Futuremark 3DMark 11 (the AMD 7970 earned 2,754); 92.9 frames per second (fps) and? 64.2fps in DiRT 3, at 1,920 by 1,200 and 2,560 by 1,600, respectively (the AMD 7970 manage 81.2fps and 57.5, respectively, at the same resolutions), 70.3fps and 50.7fps in Lost Planet 2, versus 54.9fps and 41.3fps for the AMD 7970 (again at the same resolutions); and 41.1fps and 23.6fps in Total War: Shogun 2, compared with 31fps and 18.1fps for the AMD 7970.

But the GTX 680 was not an all-around leader?sometimes the AMD 7970 trumped it. The latter attained 59.2fps and 37.4fps in Aliens vs. Predator (at 1,920 by 1,200 and 2,560 by 1,600 respectively); Nvidia?s model managed 52fps and 31.7fps in the same runs. In H.A.W.X. 2, the GTX 680 was strongly ahead at 1,920 by 1,200 (143fps versus 131fps), but the two cards tied at 2,560 by 1,600 (each made 94fps). And on the synthetic Unigine Heaven 3.0 benchmark test, the GTX 680?s win at 1,920 by 1,200 with 43.6fps (versus 40.5fps for the 7970) was softened a little by AMD?s card scraping just to the front at 2,560 by 1,600: 29.3fps versus 28.9. These are small differences, to be sure, but they show that the GTX 680?s lead is not always a commanding one.

In the broader scheme of things, however, the GTX 680?s picture looks even better. We pitted it against both AMD?s and Nvidia?s dual-GPU cards from the last cycle, the Radeon HD 6990 and the GeForce GTX 590, and it held its own surprisingly well. Its 3DMark 11 score was darn close to those of the bigger cards (3,287 for the GTX 590 and 3,436 for the 6990). So were its frame rates in DiRT 3 (97.23fps and 100.23fps for the 6990 and the GTX 680 at 1,920 by 1,200; 70.5fps and 70.3fps at 2,560 by 1,600); Heaven (47.8fps and 50.7fps; 34.5fps and 33.7fps); and Total War: Shogun 2 (43.5fps and 41.7fps at 1,920; the AMD also rated 25.9fps at 2,560 by 1,600, a resolution the GTX 590 could not handle). And in Lost Planet 2, the GTX 680 actually matched the GTX 590 at 1,920, and was just slightly lagging at 2,560 by 1,600 (52.6fps for the GTX 590; the 6990 was noticeably further behind).

As attractive as its performance numbers generally are, however, the GTX 680 is drop-dead gorgeous when you consider its power usage. We measured full-system power usage for a test PC loaded with each of the aforementioned cards using an Extech Datalogger. The biggest draw came from the Nvidia GTX 590, which pulled about 136 watts when idle and 445 watts under load (3DMark 11 running at 2,560 by 1,600 with all the detail settings maxed out); the AMD 990 drew a marginally more respectable 131 watts and 432 watts under the same conditions. Dropping back to the single-GPU models, the GTX 680 practically matched the AMD 7970 when idle (both drew about 99 watts), but flattened it under load: Whereas the AMD 7970 pulled 342 watts, the GTX 680 drew only 298. Remember: This is a card that not only keeps pace with, and usually surpasses, the 7970, but in some cases only barely trails the dual-GPU AMD 6990 and Nvidia GTX 590.

Given all this, we can enthusiastically recommend the Nvidia GeForce GTX 680, and bestow on it our Editors? Choice award. Just make sure you know what you?re getting: a card that?s fast, but not always the fastest, in its class, and achieves this without enslaving you to your electricity provider. If you demand the absolute best frame rates all of the time, you?re admittedly better off with one of the dual-GPU behemoths. But we think the GTX 680 is powerful enough?and power-efficient enough?to recommend it above them in all but the most extraordinary situations. We imagine AMD will surmount these new performance and power differentials soon enough, but until then, if you want a truly remarkable single-GPU video card, the GTX 680 is the card you want.

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