Multi-GPU support was a fascinating technology back when it launched, allowing users to pair up two or more graphics cards for higher performance rather than purchasing a single and costlier graphics card. However, a decade has gone by and there has been no significant progress in the multi-GPU field with many vendors, AMD & NVIDIA, dropping support for it entirely due to poor scaling across multiple cards, non-optimization in applications and various other issues. But this doesn't mean that users who want to try out multi-GPU cannot do so anymore, and that's what the folks over at Uniko's Hardware have just done so, pairing up a Radeon RX 5700 graphics card with a Radeon RX 5600 XT to see how they perform.
AMD Radeon RX 5700 & Radeon RX 5600 XT Paired Up In Multi-GPU - 70% Boost In Performance But With Lots of Issues
As stated, AMD and NVIDIA have almost entirely dropped support for Multi-GPU on their current generation of graphics cards. AMD's Crossfire is no more but that has been replaced by XDMA, a protocol that links GPUs over the PCIe interface. NVIDIA, on the other hand, allows multi-GPU only on its high-end graphics cards through the NVLINK interconnect with the SLI days far gone. While AMD's XDMA link doesn't allow you to mix and match two separate graphics cards, with DirectX 12's and Vulkan API's mGPU explicit adapter, you can combine two different GPUs with different configurations.
Coming to the testing, there were a certain number of things noted by the Uniko, especially games support as regardless of how optimized DirectX 12 API could be for AMD hardware, the game title itself needs further optimization to support explicit mGPU functionality. There were a vast majority of games that couldn't even run with the only titles that ran without crashing being Rise of The Tomb Raider and Strange Brigade.
The platform used for testing featured an AMD Ryzen 7 3700X 8 core processor, an ASRock X570 Taichi motherboard, 16 GB of DDR4 memory running at 3200 MHz, a combination of 512 GB SSD and a Terabyte HDD. The graphics cards were the main component of the testing which included the ASUS Radeon RX 5700 Dual EVO (8 GB) and the ASUS Radeon RX 5600 XT TUF3 EVO Gaming (6 GB). The latest AMD Adrenaline Radeon Software 20.2.1 drivers were used.
There are various benchmarks including power consumption figures which are something very important to consider here. The Radeon RX 5700 and Radeon RX 5600 XT combo consumes just around 450W (446.4W in actual) power at full load. A single Radeon RX 5700 consumes 259.6W of power. That's about 71% more power out of the wall for the combo over the standard RX 5700.
In the synthetic 3DMark Time Spy benchmark, the RX 5700 and RX 5600 XT combo scores 14,156 points in the graphics and 13,1342 in the overall test. The Radeon RX 5700 alone scores 8217 in the graphics and 8508 in the overall test. This is a 72% increase in performance over the single Radeon RX 5700 graphics card.
Moving on to real games, Strange Brigade at Ultra (DX12) delivers an average frame rate of 228.8 FPS and 151.2 FPS in 1% lows. A single Radeon RX 5700 delivers an average frame rate of 138.6 FPS and 98 FPS in 1% lows. This is a 65% increase in the average FPS. In Rise of The Tomb Raider DX12, the combo pushes 191.3 FPS at average and 111.5 FPS in 1% lows. The single Radeon RX 5700 can push 116.9 FPS at average and 87.4 FPS in 1% lows. We see a 71.6% increase in performance in The Rise of The Tomb Raider. One thing that is consistent throughout the benchmark is how the overall performance scales with the power figures. For a 71% increase in power, the combo delivers just around the same performance improvement.
At the end of the day, even this testing wasn't without its share of issues with Uniko reporting stutter and tearing in games throughout the testing. Once again, we are brought back to where we started off this topic from and that is the abandonment of mGPU functionalities by developers and the GPU vendors themselves, at least in the gaming segment, over the years. We hope that there's a big revival of multi-GPU in the coming years but the current state just doesn't warrant the need to invest in a second graphics card as a single high-end GPU can deliver much better performance at a consistently smooth frame rate and while consuming much lower power.