AMD RX Vega 56 review: even if you could afford it, you probably shouldn’t buy one | PCGamesN

AMD RX Vega 56 review: even if you could afford it, you probably shouldn’t buy one

The RX Vega 56 is the second-tier graphics card in AMD’s top range of GPUs, but is still priced well beyond its performance

AMD Radeon RX Vega 56 review

The AMD Radeon RX Vega 56 is the second-tier graphics card in the red team’s top range of GPUs. That would normally make it our price/performance favourite, but that’s just not the case this time around.

The Vega 56 was always onto a bit of a hiding to nothing. Team Radeon’s Sith-inspired rule-of-two chip design means every GPU they create eventually gets released as a pair of gaming graphics cards. So, following on from the AMD RX Vega 64, comes their lower-spec RX Vega 56, struggling to keep up with a GTX 1070 and beaten bloody by Nvidia’s GTX 1070 Ti. Poor lamb.

Much of AMD’s Vega struggles can be traced back to the choice of HBM2 as the memory technology to be used across the professional and consumer variants of the Vega design. If AMD had simply opted for the traditional GDDR5/X memory Vega would have been here a lot sooner, and, importantly, a lot cheaper. Unfortunately it seems changing the memory compatibility is a toughie or we might have seen lower-spec cards.

Bless the ol’ AMD Vega architecture, it’s had a bit of a hard time. Since it was first announced, in hushed whispers, as the first high-end Radeon GPU in an age, it’s been hailed both as the saviour of AMD’s graphics division and the architecture that might damn it. In all honestly, it’s neither.

The lack of stock and confusion over pricing initially left a bit of nasty taste in the mouth, with accusations flying around about the original RX Vega 56’s $399 price given out to reviewers being only a short-term deal.

That’s a moot point now, with the nightmare of cryptocurrency miners grabbing all available GPUs. Both Vega cards are now almost as rare as a reasoned Twitter debate, making prices still artificially inflated at $480 (£452) even after the crypto market has calmed down.

AMD RX Vega 56 specs

AMD Radeon RX Vega 56 specs

There’s not a huge difference between the GPUs at the heart of the top-end RX Vega 64 and this lower-caste RX Vega 56. As the name suggests, the second-tier card has 56 compute units (CUs) compared with the 64 CU count of the higher-spec card. That means AMD has jammed 3,584 GCN cores into the RX Vega 56 instead of the previous card’s 4,096 GCN cores.

Other than that it’s purely a case of some tweaked power settings and lower clockspeeds – everything else is identical, down to the cooling design. That means we’re still talking about 8GB of HBM2 video memory and a 2,048-bit bus. It’s the same on-die configuration that makes the Vega 10 GPU a 486mm2 mammoth (the GP102 used in the GTX 1080 Ti is just 314mm2 for comparison) with 12.5bn transistors inside it.

RX Vega 64 RX Vega 56 RX 580 GTX 1080 Ti
GPU AMD Vega 10 AMD Vega 10 AMD Polaris 20 Nvidia GP102
Architecture GCN 4.0 GCN 4.0 GCN 4.0 Pascal
Lithography 14nm FinFET 14nm FinFET 14nm FinFET 16nm FinFET
Transistors 12.5bn 12.5bn 5.7bn 7.2bn
Die size 486mm2 486mm2 232mm2 314mm2
Base clockspeed 1,247MHz 1,156MHz 1,257MHz 1,480MHz
Boost clockspeed 1,546MHz 1,471MHz 1,340MHz 1,645MHz
Stream Processors 4,096 3,584 2,304 3,584
Texture units 256 256 144 224
Memory Capacity 8GB HBM2 8GB HBM2 8GB GDDR5 11GB GDDR5X
Memory bus 2,048-bit 2,048-bit 256-bit 352-bit
TDP 295W 210W 185W 250W

There’s no liquid-chilled version of the RX Vega 56, nor are there any super-sexeh Silver Shroud variants. From the looks of things, AMD only made maybe five of either anyway, and I think those just went out to friends and family…

In terms of the actual Vega GPU architecture, we’ve gone into detail about what AMD’s engineers have been trying to create in our RX Vega 64 review. Essentially, they’re calling it their broadest architectural update in five years which is when AMD unleashed the original Graphics Core Next (GCN) design – and it brings with it some interesting new features.

One of which is the Infinity Fabric interconnect, binding the GPU with all the other components in the chip, making it a more modular architecture than previous generations. It’s also the key factor in making multi-GPU packages in the future. There’s also the new compute unit and AMD’s high-bandwidth cache controller (HBCC) too, offering the promise of the tech improving as more developers start taking advantage of it.

AMD RX Vega 56 benchmarks

AMD Radeon RX Vega 56 benchmarks

3DMark Time Spy benchmark

PCGamesN Test Rig: Intel Core i7 8700K, Asus ROG Strix Z370-F Gaming, 16GB Crucial Ballistix DDR4, Corsair HX1200i,
Philips BDM3275

AMD Vega 56 performance

AMD Radeon RX Vega 56 performance

The big challenge for the RX Vega 56 – outside of trying to magic up affordable stock for people to actually buy – is to push past the similarly priced Nvidia competition. Just as the RX Vega 64 was supposedly priced to go head-to-head with the GTX 1080, the RX Vega 56 was released into the wild with the GTX 1070 in its sights. Unfortunately Nvidia hit back with the GTX 1070 Ti

Like the RX Vega 64’s attempts to overthrow the GTX 1080, the Vega 56 struggles against its targets. As we said about the flagship Vega GPU, it’s an architecture which seems to have been primarily designed for a gaming future that’s yet to have been created. As such, it’s rather lacklustre in its legacy gaming performance.

With games built using the last-gen DirectX 11 API the second class Vega is left trailing in the wake of the GTX 1070, let alone the GTX 1070 Ti. But when you start to bring in tests based around the newer DirectX 12, or Vulkan, instruction sets, Vega’s modern architectural design allows it to occasionally take the lead.

Unfortunately, despite DX11 now being very much a legacy API, with DX12 being over a year old, the majority of PC games are still being released using the older system. And that means for the majority of PC games that come out over the next six months, at least, the GTX 1070 is likely to retain that performance advantage.

Granted, Vega’s performance improvements in DX12 and Vulkan are encouraging for how it’ll fare down the line, if they become the dominant APIs, but right now anyone lucky enough to be able to find the RX Vega 56 for a decent price is still going to be paying the same money for a card that struggles to beat a smaller, more efficient, two year-old GPU in pretty much every game that’s in their Steam library.

That’s not the only competition for the RX Vega 56, however, as there’s also the small matter of fratricide. As is its wont, despite the $100 price difference in their relative SEP, AMD hasn’t made sweeping changes to the core configuration of the two Vega variants. Essentially, the RX Vega 56 is simply operating with 12.5% fewer cores, yet in performance terms is only ever around 7-10% slower.

That means there’s a good chance gamers will end up going for this mildly chopped down Vega instead of the much more expensive card. Or they would be if the cards were consistently available for reasonable prices. We’ve seen etailers where there are RX Vega 64 SKUs available for around the same price, sometimes less, than that shop’s cheapest available RX Vega 56.

Yeah, Vega’s weird.

AMD Vega 56 verdict

AMD Radeon RX Vega 56 verdict

The overall design of the Vega architecture seems to have been about laying a marker in the sand, defining a branching point for future generations of AMD’s GPU technology. It’s sacrificed legacy gaming performance for the promise of future applications of its smart-looking, though largely unused, feature set. The little extras the Vega architecture has baked into it look like they could be genuinely game-changing… but only if developers actually end up taking advantage of them. And that’s a pretty big if.

If it was guaranteed that the HBCC and Rapid Packed Math shenanigans were going to be employed across the board, and not just by AMD best-buds Bethesda, then the new Radeon tech would definitely be the one to go for over the old-school Nvidia design. But it’s not a sure thing, and we don’t really know what performance improvements these Vega features might offer either.

Wolfenstein II: The New Colossus has shown some impressive Vega performance in the face of the GTX 1080 competition, with AMD’s traditional Vulkan speed-wins in the low-level API. But Vega is showing greater gains than the Polaris architecture, which would indicate there is something to the Rapid Packed Math stuff. We’re going to be doing some more investigating on that in the future.

If you were spending around $400 on a graphics card today – even if there were RX Vega 56’s available at their suggested price – it would still be difficult to make the Radeon recommendation. It’s the more advanced architecture, but in raw performance terms the smaller, slightly cheaper, more efficient Nvidia GPU is likely to get you higher frame rates in more of the games you’re playing at the moment.

If AMD could have priced Vega more aggressively against the still-strong two year-old Nvidia Pascal architecture, then it would have a better chance of taking the market by storm, but unfortunately the price of HBM2 is a big sticking point. And with AMD reportedly losing $100 on each card sold at the suggested price, it looks like it’s done all it can on that front.

I like what AMD is trying to do with Vega, but sacrificing current performance for the vague chance of higher frame rates in a few future games is too much of an ask for most of us PC gamers.

AMD Radeon RX Vega 56

The Vega 56 should be the price/performance hero of AMD's top GPU architecture, but it's pricing itself out of the running, with gaming frame rates well short of the competition.