Review: EVGA GTX 970 SSC in SLI vs. Titan X and R9 295X2

Introduction, Testing Methodology

Evaluating graphics hardware is relatively straightforward when one compares a certain GPU against another. Bigger, more powerful graphics processors outmuscle smaller ones, albeit at the cost of increased heat and energy consumption.

The situation becomes more nebulous once multi-GPU setups - either on a single card or on two boards - are thrown into the equation. Common sense dictates that for smoother performance it is better to opt for a single-GPU graphics card than two lashed together via SLI or CrossFire, but there's significant value to be had when accepting the minor foibles associated with a multi-GPU rig.

A case in point is the Radeon R9 295X2, available for below £500 and able to give the much dearer GeForce GTX Titan X a bloody nose in benchmarks. Yet while the monstrous Titan X may not be quite so fast in pumping out frame rates, the refinements of a single-GPU architecture ultimately provide a better gaming experience when dialled to high image-quality settings at a 4K resolution.

We can add another wrinkle into this performance mix by looking at the results of the GeForce GTX 970 GPU in two-card SLI. The recipe is simple; take a well-overclocked single card - the EVGA GTX 970 SSC is as good a bet as any - add another, and see what happens once pressed through the benchmark wringer.

And we did precisely this with a second card from EVGA. The key aspects to lookout for are: a) average and minimum performance at high resolutions b) what limitations, if any, are imposed by having a mere 3.5GB 4GB framebuffer at 4K and c) just how slow and stutter-inducing the final, slowest one per cent of frames are.

Let's delve into this analysis by seeing which cards are up for the fight.

Notes

All cards have been benchmarked from scratch using the latest drivers at the time of testing.

To minimise the impact of any CPU bottlenecks, our test platform is configured with a quad-core Intel Core i7-4770K overclocked up to 4.4GHz. 16GB of Corsair Vengeance Pro DDR3 is set to run at 1,866MHz using the built-in XMP profile.

For our ultra-high-end benchmark suite, we have an array of games tested at full-HD (1,920x1,080) QHD (2,560x1,440) and 4K (3,840x2,160) resolutions. In order to maintain playable framerates in the latter mode, the level of anti-aliasing may be reduced and any such changes are highlighted using bold in the above table. Readers should note that, despite running with lowered settings, games often look considerably better at 4K as a result of the huge increase in on-screen pixels.

Where applicable, any vendor-specific enhancements such as PhysX and TressFX are disabled to help even the playing field.

In-game benchmark results are recorded as average frames per second, and to provide further analysis, we report the percentage of frames rendered within a specified time, as well as the time taken to render the slowest one per cent of frames during the benchmark run. We choose 25ms at 4K which equates to a full 40 frames over a second. This number is chosen for two reasons: it's the lowest we reckon is passable for smooth gameplay and, secondly, is where refresh-rate-adjusting technologies such as G-Sync and FreeSync begin to have a real frame-smoothing impact.