For the first time in years, we’re getting a dual-GPU card coming to market. In a twist, this Radeon Pro Vega II is coming to Mac Pro users. What is this card and what does it mean for professional users in general.
Multi-GPU computing has taken a bit of a hit in recent years. We no longer have access to three- and four- way SLI on Nvidia’s side and even when we did, little attention was given to game compatibility.
For a short while every flagship GPU shoved two whole GPUs onto one card. “Recent” examples includes the Titan Z, which came out in 2014 or the Radeon Pro Duo, which is notable for its sweet integrated water cooler.
Given how ridiculously fast cards like the RTX Titan or 2080 Ti are, there’s little incentive to make dual-GPU cards. Especially since you can still slot two cards next to each other and either use them both for GPU computation or use them for rendering applications like games, albeit with some scaling loss.
Now AMD have come out of left field with what is surely the most advanced dual-GPU design to date. Unfortunately, only Mac Pro users need apply.
Holy Giant GPU Card Batman
The card in question is the Radeon Pro Vega II and it is simply the fastest single-card GPU solution you can buy. If you are happy with also buying a Mac Pro to slot it into. In fact, you can stick TWO of these cards in the compatible Mac Pro machines.
The card is based on the Vega 20 7nm chip, with each GPU coming with 32GB of HBM, providing a insane 1TB/s of bandwidth. The two GPUs talk to each other using AMD’s Infinity Fabric. The same technology you’ll find helping Ryzen dies communicate, with up to four CPU dies communicating at high speed.
The end result is a card that can provide a claimed 14 TFLOPS of single-precision floating point operations and twice that for half-precision.
The main reason this card can’t be used in an existing PC is the custom connector design. It has two inline PCIe connectors, with the second connector used for additional power delivery and to facilitate Thunderbolt 3 bandwidth. It allows for up to 475W of power without the need for external PCIe power connectors.
Coming to PC?
There is absolutely no word from AMD on whether a similar product will be coming to PC. We don’t see any technical reason why they could not. Dropping the second PCIe connector, Thunderbolt 3 and simply adding PCIe external power connectors should be no issue. However, this may be an exclusive partnership with Apple, at least for now. The appeal of Mac Pro machines has been waning as Apple leans into its phone and digital ecosystem. Pro hardware from Apple has often lagged years behind what you could build for the same money on the PC side of things. Now, owning a Mac Pro is literally the only way to have this card (or a pair of them) working on your GPU computation applications.
Working Out The Bugs How useful dual-GPU cards are depends on the application you want to run. Multi-GPU general computation is becoming quite mature and many professional applications can efficiently split workloads among multiple cards. Of course, that diminishes the inter-GPU communication advantages you get with the dual-GPU design. What we still lack is a reliable way to make multiple GPUs appear as one GPU to software. So that GPU workloads can be split among these chips at a hardware level. Modern APIs like DX12 go a long way to marrying GPUs together, even ones that aren’t identical, but it’s still hit and miss on a software level.
It is a problem we’re confident will be solved sooner rather than later. With GPUs now hitting a 7nm process and most likely the limit of silicon chip frequency, the only way up is to start adding more dies. The Pro Vega II might very well be the first real move towards shifting GPU architecture into multi-die configurations with little or no overhead loss. On the other hand, it might also be a temporary way to market Mac Pro computers as the GPU performance kings. As professional PC workstation enthusiasts, we’ll be watching what AMD do with this idea very closely.
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