While it isn't nearly as powerful, AMD's R9 290 costs $40 less than a stock GTX 970, and AMD offers three free games of your choice when you purchase a R9-series graphics card. You can choose from a stable of 27 solid, but mostly slightly older titles, though you'll also find Alien: Isolation, Sniper Elite 3, and some Star Citizen modules, as well as a handful of indie options. That could be a deciding factor for frugal gamers, though many of the games can be picked up fairly cheap in a Steam sale or the odd Humble Bundle. Still, everybody likes free stuff, and this is a compelling offer.
Mantle and other extra features
Beyond the free games, AMD's TrueAudio and Mantle technologies are also trump cards — at least in games that support the technology. The former offloads digital audio processing from the CPU to a dedicated audio block in the GPU, comprised of Tensilica audio DSP cores, while the latter is an optional application programming interface that allows developers deeper access to your PC's hardware, opening the door for potentially enhanced performance.
The most notable Mantle frame rate increases occur in gaming rigs with limited CPU capabilities, however. Gamers purchasing ultra-high-end graphics cards likely have a decent processor to match — limiting Mantle's likely frame rate enhancements when used with the R9-series cards. But enabling Mantle was enough to push the R9 290X's frame rates slightly past the GTX 980 in Civilization: Beyond Earth's built-in benchmark at 2560x1600 resolution (measured using FRAPS starting when the screen goes black and the scene begins to load). Similar results were achieved in Sniper Elite 3: While Nvidia's cards outperformed AMD's using DirectX 11, enabling Mantle boosted the Radeon R9 290X slightly ahead of the GTX 980.
AMD also claims that enabling Mantle allows the R9 290X to juuuuust slightly triumph over Nvidia's champion at 4K resolution. I don't have a 4K monitor on hand for testing, but other sites have found that AMD's Radeon R9 290X actually beats (or at least ties) Nvidia's Maxwell cards at 4K fairly often, especially in Mantle-enabled titles.
Mantle can provide more than mere frame rate boosts however. Beyond Earth also leveraged Mantle's deeper control options to enable a "split-frame rendering" subsystem in multi-card setups, basically assigning each GPU a portion of the frame to render, rather than having the cards alternate rendering full frames, as is the norm in CrossFire and SLI setups. While this prevents raw frame rates from doubling, as you often see with multi-GPU setups, split-frame rendering reduces "microstuttering" — drastic variances in frame-to-frame rendering rates — and helps Civilization keep a smooth, responsive feel. Alas, I haven't had an opportunity to test this feature either.
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