Sure, they’ve been careful to develop products that can play perfectly to the on-the-move crowds. But products have been designed with the desktop market in mind first and foremost, with more power-conscious mobile versions being rolled out some time after. It may not be immediately apparent from this card, but nVidia’s 750 series (codenamed Maxwell) marks a very significant shift.
Gigabyte GTX 750 Ti WindForce OC 2048MB review: designed to preserve energy
Maxwell is the first series of graphics chips to be designed primarily to conserve energy. Clearly, what we’re reviewing today is a desktop part, but the chip that sits at the heart of this Gigabyte is geared towards efficiency rather than ultimate power. The secret isn’t so much in the manufacturing process (like Kepler before it, Maxwell is created using 28nm – even bigger energy savings will be possible when the smaller 20nm process is employed, probably some time in 2015). The key is in the heavily streamlined architecture, which replaces the older SMXes with new SMMes (Streaming Maxwell Multiprocessor). Whereas SMXes shared many resources with one another, each SMM will have its own dedicated version of such features as warp schedulers and instruction buffers. Kepler had to spend much of its time diverting traffic to the right place. Maxwell, in contrast, keeps its traffic streams very much more separate, so more time can be spent cruising through the data itself rather than organising it. This particular card uses the 750 Ti – a standard 750 is also available. What’s important to bear in mind is that Maxwell is often doing similar amounts with considerably less. Specification for specification, it doesn’t look spectacular when set alongside, for example, the Kepler-based 650 and 650 Ti products.
Gigabyte GTX 750 Ti WindForce OC 2048MB review: stream processors
The 750 Ti’s 640 stream processors is easily eclipsed by the 650 Ti’s complement of 768. Texture handling takes a considerable hit with Maxwell’s new technology, and the 750 Ti’s 40 texture units look rather paltry next to the 64 of the 650 Ti – even the sub-£90 650 packs 32 texture units. The 750 Ti does hit back with some good core speeds, but even with the added boost and the benefit of Gigabyte’s overclocking, nothing can atone for the paucity of texture units. The 750 Ti’s texture fill rate of 44.4GT/sec is only marginally ahead of the non-overclocked 650 (on 33.9GT/sec), and truly struggles against the 650 Ti (on 59.4GT/sec).
Gigabyte GTX 750 Ti WindForce OC 2048MB review: memory interface
All of these chips are saddled with 128bit memory interfaces, although the 750 Ti does offer twice the memory (2GB) of the typical 1GB 650 and 650 Ti products. Its memory bandwidth – 86.4GB/sec – is broadly identical to that of the 650 Ti, and marginally ahead of the 80GB/sec of the standard 650. The 750 Ti does up the video encoding though, using its new NVENC to deliver more encoding speed for less power – note that the aim here is conserving energy rather than boosting encoding to new levels of performance.
Gigabyte GTX 750 Ti WindForce OC 2048MB review: performance tests
So far, relatively unimpressive. Put the 750 Ti through its paces, and it becomes quickly apparent that this product extracts far more from its relatively modest parts. The performance is very similar to that of the 650 Ti. The latter is better in tough texture-heavy games played over high resolutions. In Crysis 3, for example, the 650 Ti scores 28.0 to the 750 Ti’s 27.7fps at a resolution of 1900×1200, and 19.4fps to the 750 Ti’s 18.8fps at 2560×1600. In Bioshock Infinite Rage, the 650 Ti is again marginally better, notching up figures of 60.2 and 35.7fps against 57.9 and 34.6fps for the 750 Ti. In slightly less demanding games, the 750 Ti hits the highest figures, though, getting 66.3fps and 56fps in BattleForge, as opposed to 63 and 54.8fps for the 650 Ti. In the also-relatively undemanding Stalker Call of Pripyat, the 750 Ti is victor again, snagging 67.3 and 59.5fps to the 650 Ti’s 65.1 and 58.6fps. So merely in terms of performance, the 750 Ti and 650 Ti are pretty much identical. If you want lots and lots of textures, the 650 Ti will be marginally better. In older less-detailed games, the 750 Ti ekes out a small lead. What is rather more surprising, though, is that the 750 Ti essentially keeps pace while putting out much less power. This chip has a TDP of 60 watts, against the 650 Ti’s 110 watts. Those figures are actually a little exaggerated, although we did find that the 650 Ti was generally putting out an additional 23-30 watts during load testing. (See all budget graphics card reviews.)
