After what seemed like an age of waiting and unrelenting hype, the AMD Vega GPUs have arrived. And, in a bit of a silicon contradiction, they’ve managed to be simultaneously disappointing and completely sell out.
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The Vega launch feels classically AMD, in that they’ve worked hard to create some interesting hardware, with some unique selling points, but it’s a little too forward-thinking to be of a lot of use right now. And there’s also the potential problem that when the forward-thinking tech does become useful this iteration of it will be outdated.
Unfortunately, right now, the AMD RX Vega cards suffer by comparison to their smaller, more efficient, and more powerful Nvidia competition.
AMD Vega reviews
- AMD Radeon RX Vega 64 review: a high-end GPU waiting on a future it’s trying to create
- AMD Radeon RX Vega 56 review: even if you could buy one, you probably shouldn’t… yet
AMD Vega news
- XFX tease AMD RX Vega design, but no launch date for patient customers
- AMD’s Vega isn't finished yet, Vega 11 goes into production to replace Polaris
- Who's going to make custom AMD RX Vega 64 cards? Short answer: maybe no-one
- Vega’s innards aren’t game-ready, consumer-optimised versions are coming
- AMD Vega is now so good for crypto-mining it'll probably be sold out forever
At the moment, there are only a pair of gaming-focused AMD RX Vega cards: the Radeon RX Vega 64 and the Radeon RX Vega 56. These both essentially sport the same Vega 10 GPU at their hearts, utilising the full 14nm, 12.5bn transistor silicon, with only a few small cuts to make up the lower-spec card.
There might be custom versions of the RX Vega cards coming sometime this year. Maybe. At the moment there are so few GPU packages actually coming out of AMD that their board partners are struggling to get even just the reference models out into the wild, let alone ones with their own coolers and overclocked silicon.
Asus have shown off an early STRIX version, to a rather muted response, but MSI, Gigabyte, and even AMD big boys, Sapphire, are being rather coy about whether there are going to be any custom cards from them. It looks like we might get some RX Vega 56 variants, but the flagship RX Vega 64 looks dead in the water.
There will be Vega 11 GPUs coming soon - they’re moving into production at the moment - which ought to replace the current 500-series, Polaris-GPU-based cards. Given that those graphics cards are barely available anyway that’s definitely a positive on the horizon. When exactly that means we’re likely to see them, and what impact they’re going to have on the market, we’re not too sure.
The tricky thing is they can’t really come with the second-gen high-bandwidth memory (HBM2) given that’s one of the main reasons behind the high price of the current Vega stock, so they’re going to have to rely on GDDR5 or GDDR5X. If they want GDDR6 they’ll have to wait until sometime in early 2018.
They’re also not really going to be able to offer much greater performance than the Polaris generation. There’s not a great performance chasm between the RX 580 and the RX Vega 56, so where are the smaller-scale Vegas going to sit in AMD’s current GPU stack?
And, also, how much of the intriguing Vega architecture are they going to contain?
AMD Vega architecture
The new AMD Vega architecture represents what they’re calling the most sweeping architectural change their engineers have made to the GPU design in five years. That was when the first Graphics Core Next chips hit the market and this fifth generation of the GCN architecture marks the start of a new GPU era for the Radeon team.
Fundamental to the Vega architecture, represented here by the inaugural Vega 10 GPU, is the hunt for higher graphics card clockspeeds. The very building blocks of the Vega 10, the compute units, have been redesigned from the ground up, almost literally. These next-generation compute units (NCU) have had their floorplans completely reworked to optimise and shorten the physical wiring of the connections inside them.
They also include high-speed, mini memory SRAMs, stolen from the Zen CPUs and optimised for use on a GPU. But that’s not the only way the graphics engineers have benefitted from a resurgent CPU design team; they’ve also nabbed the high-performance Infinity Fabric interconnect, which enables the discrete quad-core modules, used in Ryzen and Ryzen Threadripper processors, to talk to each other.
Vega uses the Infinity Fabric to connect the GPU core itself to the rest of the graphics logic in the package. The video acceleration blocks, the PCIe controller and the advanced memory controller, amongst others, are all connected via this high-speed interface. It also has its own clock frequency too, which means it’s not affected by the dynamic scaling and high frequency of the GPU clock itself.
This introduction of Infinity Fabric support for all the different logic blocks makes for a very modular approach to the Vega architecture and that in turn means it will, in theory, be easy for AMD to make a host of different Vega configurations. It also means future GPU and APU designs (think the Ryzen/Vega-powered Raven Ridge) can incorporate pretty much any element of Vega they want to with minimal effort.
The NCUs still contain the same 64 individual GCN cores inside them as the original graphics core next design, with the Vega 10 GPU then capable of housing up to 4,096 of these li’l stream processors. But, with the higher core clockspeeds, and other architectural improvements of Vega, they’re able to offer far greater performance than any previous GCN-based chip.
The new NCUs are also capable of utilising a feature AMD is calling Rapid Packed Math, and which I’m calling Rapid Packed Maths, or RPM to avoid any trouble with our US cousins. RPM essentially allows you to do two mathematical instructions for the price of one, but does sacrifice the accuracy. Given many of today’s calculations, especially in the gaming space, don’t actually need 32-bit floating point precision (FP32), you can get away with using 16-bit data types. Game features, such as lighting and HDR, can use FP16 calculations and with RPM that means Vega can support both FP16 and FP32 calculations as and when they're necessary.
We’ll see the first game supporting RPM, and other Vega-supported features, like asynchronous compute, when Wolfenstein II: The New Colossus launches. The Far Cry 5 developers have also come out in support of RPM, and could make FC5 very Vega-friendly. 3D technical lead, Steve Mcauley, has gone on record stating: “there’s been many occasions recently where I’ve been optimising shaders thinking that I really wish I had rapid packed math available to me right now. [It] means the game will run at a faster, higher frame rate, and a more stable frame rate as well, which will be great for gamers.”
The Vega architecture also incorporates a new geometry engine, capable of supporting both standard DirectX-based rendering as well as the ability to use newer, more efficient rendering pipelines through primitive shader support. The revised pixel engine has been updated to cope with today’s high-resolution, high refresh rate displays, and AMD have doubled the on-die L2 cache available to the GPU. They have also freed the entire cache to be accessible by all the different logic blocks of the Vega 10 chip, and that’s because of the brand new memory setup of Vega.
AMD’s Vega architecture uses the second generation of high-bandwidth memory (HBM2) from Hynix. HBM2 has higher data rates, and larger capacities, compared with the first generation used in AMD’s R9 Fury X cards. It can now come in stacks of up to 8GB, with a pair of them sitting directly on the GPU die, making the memory both more efficient and with a smaller footprint compared to standard graphics chip designs. And that could make it a far more tantalising option for notebook GPUs.
Directly connected with the HBM2 is Vega’s new high-bandwidth cache and high-bandwidth cache controller (HBCC). Ostensibly this is likely to be of greater use, at least in the short term, on the professional side of the graphics industry, but the HBCC’s ability to use a portion of the PC’s system memory as video memory should bare gaming fruit in the future. The idea is that games will see the extended pool as one large chunk of video memory, so if tomorrow’s open-world games start to require more than the Vega 64’s 8GB you can chuck it some of your PC’s own memory to compensate for any shortfall.
"You are no longer limited by the amount of graphics memory you have on the chip," AMD’s Scott Wasson explains. "It's only limited by the amount of memory or storage you attach to your system."
The Vega architecture is capable of scaling right up to a maximum of 512TB as the virtual address space available to the graphics silicon. Nobody tell Chris Roberts or we won’t see Star Citizen this side of the 22nd century.
AMD Vega performance
The thinking behind Vega seems to have been to put the RX Vega 64 up against the GTX 1080 with the RX Vega 56 going head-to-head with the GTX 1070. Unfortunately, with most games on the market today, the AMD cards are always that little bit behind the Nvidia GPUs. It’s only when you start looking at the more modern DirectX 12 and Vulkan APIs that the Vega architecture starts to show its worth.
It’s this bifurcated performance - poor in legacy games and impressive with modern software - that makes the Vega cards difficult to recommend right now. AMD’s classic ‘fine wine’ approach may mean that when architecture matures, and devs start to use the impressive feature set to its fullest, the AMD cards might be able to push past their Nvidia rivals.
But that’s scant comfort to anyone wanting class-leading performance for every game in their Steam libraries, or even just the games they’re playing at the moment. There is a little light at the end of the overclocking tunnel however, with tweakers uncovering increased capabilities of the card, unlocked by undervolting the GPU. But that’s a whole other story...
AMD Vega availability
There are still precious few RX Vega cards available right now. And those you can buy are often vastly overpriced for the performance they can deliver. There are some pre-order cards available at both Amazon US and Amazon UK, but the smaller-scale retailers are where you’re more likely to find better priced cards.
The US is a mighty tricky place to try and pick up a Vega, with Newegg struggling to offer anything that isn’t pricing the new Radeons out of relevance.
It’s a little better on the verdant shores of the UK, where the likes of Overclockers and Scan have some reasonably priced stock and pre-orders on cards actually at the contentious price AMD launched the cards with.
AMD RX Vega 64 prices
AMD RX Vega 56 prices
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