EVGA GTX 680 Classified
The Classified series comprises the highest-performance air-cooled cards that EVGA offers.
The Classified card differs from its rivals in several ways. First, the EVGA GTX 680 Classified includes a staggering 4GB of frame buffer memory. Second, it uses two 8-pin connectors, as opposed to the one 6-pin/one 8-pin power configuration that most other GTX 680 cards use. The EVGA card also relies on a single cooling fan, rather than usual two or more fans. Finally, the card is unusually tall, at 5.94 inches, so you'll need to make sure that your case has sufficient height clearance to accept the card. The standard height for a PCI Express slot is 4.2 inches.
Asus GTX 680 DCII TOP
The "DCII" in the name stands for "DirectCU II." Asus uses a direct-contact copper heat sink to assist in cooling the card.
This is a massive card. Though not not quite as tall as the EVGA card, it occupies three PCI Express slot spaces inside a PC. It's also longer, at 11.8 inches, so you'll need a fairly deep case to hold the card. Your choice of motherboards is an important factor, as some vertically mounted SATA ports may be inaccessible to the GTX 680 DCII TOP.
In return you'll get one of the most aggressively factory-overclocked cards on the market. Despite the exceptional 1137MHz core clock (which exceeds 1.2GHz in boost mode), the card is exceptionally quiet. You can hear the dual cooling fans spin up under load, but the Asus card is noticeably quieter than the EVGA card. Though idle power is slightly lower, the higher boost clock leads to more-demanding power draw under load. So when the card is running under a heavy 3D-rendering load, it consumes about 30W more than the EVGA card does when similarly occupied.
Sapphire Radeon HD 7970 Dual X OC
The Sapphire Dual X is the only card of the three reviewed here that is based on AMD's Radeon HD 7970 GHz Edition--yet it doesn't quite clock at 1GHz, except under boost conditions.
The Dual X isn't Sapphire's highest-end card, however, so the conservative setting isn't terribly surprising. The card has a more conventional size than the other two cards, as well. It's a full 11 inches long but only 4.7 inches tall, and it takes up two slot spaces. The dual-fan cooling system shroud is shaped to lessen the likelihood of problems involving motherboard ports, though the card's length could be an issue in relation to some motherboards and some relatively shallow PC cases.
As we'll see shortly, the Radeon HD 7970 GHz edition tends to consume more power under load than the GTX 680.
We ran all of our performance and power tests on our standard graphics test system, which has the following components and features:
3.3GHz Intel Core i7 3960X CPU
Asus P9X79 Deluxe motherboard
Intel RT2011 sealed liquid CPU cooler
16GB Corsair DDR-1600 memory (quad-channel)
Corsair AX1200 power supply
1TB Seagate 7200.12 hard-disk drive
Asus Blu-ray reader/DVD writer
Corsair Graphite 600T case
We did not overclock the system. We used a Watts Up Pro USB power meter to collect system power data. All of our game test results are reported at a resolution of 2560 by 1600 pixels, with 4x multisampling antialiasing enabled.
Our testing regimen includes two synthetic 3D benchmarks and six game benchmarks for evaluating performance:
3DMark 2011, which simulates game rendering and GPU compute tasks.
Unigine Heaven, which can hammer a GPU's hardware tessellation engine.
Crysis 2, run with hardware tessellation disabled, since the game's use of tessellation is poorly implemented.
Total War: Shogun 2. Dialing up all of Shogun 2's features makes the game a serious memory hog when handling video.
DiRT Showdown. The latest version of the DiRT racing franchise implements global illumination using GPU compute.
DiRT 3. The older DiRT 3 test is more conventional in how it handles DirectX 11 rendering.
Metro 2033. This older first-person shooter can still stress graphics cards.
Batman: Arkham City. The sequel to the sleeper hit Arkham Asylum offers a series of fly-throughs at different levels to test graphics performance.