One of the most common questions we get here at Maximum PC, aside from details about our lifting regimen, is whether to upgrade to a high-end GPU or run two less-expensive cards in SLI or CrossFire. It’s a good question, since high-end GPUs are expensive, and cards that are two rungs below them in the product stack cost about half the price, which naturally begs the question: Are two $300 cards faster than a single $600 card? Before we jump to the tests, dual-card setups suffer from a unique set of issues that need to be considered. First is the frame-pacing situation, where the cards are unable to deliver frames evenly, so even though the overall frames per second is high there is still micro-stutter on the screen. Nvidia and AMD dual-GPU configs suffer from this, but Nvidia’s SLI has less of a problem than AMD at this time. Both companies also need to offer drivers to allow games and benchmarks to see both GPUs, but they are equally good at delivering drivers the day games are released, so the days of waiting two weeks for a driver are largely over.
2X NVIDIA GTX 660 TI VS. GTX 780
THE TEST: We considered using two $250 GTX 760 GPUs for this test, but Nvidia doesn’t have a $500 GPU to test them against, and since this is Maximum PC, we rounded up one model from the «mainstream» to the $300 GTX 660 Ti. This video card was recently replaced by the GTX 760, causing its price to drop down to a bit below $300, but since that’s its MSRP we are using it for this comparison. We got two of them to go up against the GTX 780, which costs $650, so it’s not a totally fair fight, but we figured it’s close enough for government work. We ran our standard graphics test suite in both single- and dual-card configurations.
The Results: It looks like our test was conclusive—two cards in SLI provide a slightly better gaming experience than a single badass card, taking top marks in seven out of nine tests.
And they cost less, to boot. Nvidia’s frame-pacing was virtually without issues, too, so we don’t have any problem recommending Nvidia SLI at this time. It is the superior cost/performance setup as our benchmarks show.
2x RADEoN HD 7790 vs. RADEON HD 7970 GHz
THE TEST: For our AMD comparison, we took two of the recently released HD 7790 cards, at $150 each, and threw them into the octagon with a $400 GPU, the PowerColor Radeon HD 7970 Vortex II, which isn’t technically a «GHz» board, but is clocked at
Two little knives of the HD 7790 ilk take on the big gun Radeon HD 7970 .
1,100MHz, so we think it qualifies. We ran our standard graphics test suite in both single-and-dual card configurations.
THE RESULTS: Our AMD tests resulted in a very close battle, with the dual-card setup taking the win by racking up higher scores in six out of nine tests, and the single HD 7970 card taking top spot in the other three tests. Also, AMD has acknowledged the micro-stutter problem with CrossFire, and promises a software fix for it, but unfortunately that fix is going to arrive right as we are going to press on July 31. Even without it, gameplay seemed smooth, and the duo is clearly faster, so it gets our vote as the superior solution, at least in this config.
GTX 660 Ti SLI
Radeon HD 7870 CrossFire
Radeon HD 7970 GHz
3DMark Fire Strike
Catzilla (Tiger) Beta
Unigine Heaven 4.0 (fps)
Crysis 3 (fps)
Shogun 2 (fps)
Far Cry 3 (fps)
Metro: Last Light (fps)
All tests, except for the 3DMark tests, are run at 2560×1600 with 4X AA.