Years in development, the new Radeon RX Vega line is finally arriving – AMD’s return to the higher-end of GPU performance after concentrating its efforts more on the mainstream and budget sectors of the market. There’s no shortage of cutting-edge tech here: the Vega processor utilises 12.5 billion transistors on a very large 486mm2 area of silicon, the chip paired with two 4GB stacks of cutting-edge HBM2 memory. It’s a bigger chip than Nvidia’s GTX 1080 Ti and it has more memory bandwidth – however, the top-end RX Vega 64 offers performance more in line with GTX 1080, while the cut-down RX Vega 56 reviewed here is clearly aimed to compete with the GTX 1070. It does this job rather well.
Before we go on, it’s worth stressing that the Vega architecture has a lot of features that may not be utilised much – if at all – today, but could make a big difference in future. For example, the double-speed FP16 support found in PlayStation 4 Pro was pulled ahead of time from the Vega spec sheet (referred to as ‘rapid-packed math’), while AMD has incorporated the most fully featured implementation of DirectX 12 features found in any GPU to date. Meanwhile, the high bandwidth cache controller is an attempt to allow the GPU fast, low latency access to memory beyond the 8GB of onboard RAM.
Elsewhere, the basic layout of Vega looks remarkably similar to the Fiji processor at the heart of the last-gen Fury X, but AMD is keen to point out that every aspect of the GPU has been retooled. There are still 64 compute units and 4096 shaders in the processor – pared back to 56 and 3854 in this cut-down model – but these are ‘new’ compute units with an extended instruction set and a more efficient design. AMD has also sought out faster clocks from the Vega silicon. The last-gen Fiji topped out at 1050MHz, Polaris was coaxed to 1450MHz while Vega is set to hit an impressive 1700MHz – although, again, expect a hit to that in the pared back Vega 56.
Hitting these clocks clearly hasn’t been easy though: even in its reduced state, Vega is undoubtedly power-hungry compared to the competition, as we’ll see later on in this review. That’s borne out by the design of the reference card we’re looking at here: it has two eight-pin power inputs, an even beefier configuration than the Titan Xp, despite its 210W board power rating. By comparison, the GTX 1070 Founders Edition only requires one eight-pin power input, making it easier to integrate with lower-end and medium level power supplies.
The Vega 56 card itself is a robust reference model from a company with a mixed history here – the new offering is an all-metal design, well-built, and features a vapour chamber heatsink (utilised on both Vega 56 and 64), a spec point Nvidia reserves only for GTX 1080, 1080 Ti and current-gen Titan products. External ports are a simple trio of DisplayPort 1.4s along with HDMI 2.0 – a good enough selection, but dual-link DVI should really be included on a card of this class. In operation, the Vega 56 has a temperature limit of 85 Celsius, but typically runs significantly under that. What’s more, there are power saver, balanced and turbo options. We’re reviewing in the default balanced mode, but turbo adds a couple of per cent to performance but increases power consumption.
|Radeon RX Vega 56||Radeon RX Vega 64||Radeon RX Vega 64 Watercooled|
|Peak FP32 Performance||10.5TF||12.66TF||13.7TF|
Before we diving into performance testing, AMD is making a very good point about a specific Radeon feature that proves transformative to gameplay – support for FreeSync. Variable refresh is a genuine game-changer, seeking to eliminate screen-tear and reducing the stutter you see when dropping frames with v-sync engaged. Once you have a VRR screen, it’s difficult to go back to a standard display. Now, of course, Nvidia has its own solution – G-Sync – and while the implementation is generally stronger and more uniform on those screens, they still command a significant price-premium. FreeSync, by contrast, is more likely to be a value-added extra with only a small cost increase. The bottom line is that the price for attaining a smooth variable refresh experience with a GTX 1070/Vega 56 level card is undoubtedly lower with AMD.
We’ll kick off our gaming analysis with a look at 1440p resolution – what we consider to be the best pixels vs performance target for running games at very high or ultra settings on this class of GPU hardware. Whether you’re using the standard 16:9 2560×1440 (as tested here), or else the ultrawide 3440×1440, you’re going to get an excellent experience from all of the cards tested here – high frame-rates and lots of eye-candy. It’s also fertile territory for FreeSync displays, a really good partner for the Vega 56.
For the arrival of RX Vega, we decided to beef up our GPU test suite with a couple of new entrants – Call of Duty: Infinite Warfare has impressed us with its immense level of optimisation and new rendering technologies. It’s also a title that generally runs better on AMD hardware (though Fury X doesn’t hold up so well here, curiously).
Also joining the fray is Ghost Recon Wildlands – the year’s best-selling game (in the UK at least). At ultra settings, this is one of the most GPU-heavy games we’ve tested, and it sucks up VRAM too, meaning that even at 1080p, the old Fury X really struggles here, artificially depressing its frame-rates the higher up the resolution chain you go.