Jarrod from Jarrod's Tech (not to be confused with our own Jarred Walton) recently reviewed AMD's new RX 6850M XT mobile flagship GPU against Nvidia's RTX 3080 mobile graphics using Asus' external XG mobile enclosures. Unfortunately for AMD, performance was rather disappointing for the RX 6850M XT in most of the games tested. Nvidia's RTX 3080 mobile was 10 to 20% faster overall while drawing a whopping 37% less power. These results are unusual for AMD's RDNA2 architecture, which we'll get to in a moment.
Testing was done on an Asus Flow Z13 2-in-1 gaming device powered by Intel's latest Core i9-12900H processor and 16GB of LPDDR5 RAM. The two discrete GPUs tested come in the form of Asus' external GPU enclosures known as ROG XG Mobiles. These enclosures house either the RTX 3080 or the RX 6850M XT and are powered by their own power supplies. These devices are connected to the Flow Z13 via a custom PCIe interface running at up to Gen3 speeds with eight lanes available.
The RTX 3080 version of the XG mobile is known as the 2021 ROG XG Mobile and comes with a maximum power rating of up to 150W. The RX 6850M XT model is the newer 2022 model and comes with a greater power rating of up to 165W.
Benchmarks
Overall, performance was clearly in favor of the RTX 3080 XG mobile unit. It came out ahead in nearly all the games tested. The full set of games consisted of Microsoft Flight Simulator, Fortnite, Metro Exodus Enhanced Edition, Forza Horizon 5, Control, Watch Dogs Legion, God of War, Dying Light 2, Cyberpunk 2077, Assassin's Creed Valhalla, Far Cry 6, The Witcher 3, Call of Duty Warzone, and Shadow of the Tomb Raider.
Out of those, Nvidia's GPU was faster in the first eleven (though it was close in three of those), while AMD's RX 6850M XT only took the lead in Shadow of the Tomb Raider, COD Warzone, and The Witcher 3. That was at 1080p, where Nvidia averaged 9% higher performance. It also came out 11% ahead at 1440p, with the same selection of games favoring AMD and Nvidia's solutions.
Moving up to testing at 4K, the average FPS difference between the RX 6850M XT and the RTX 3080 increased to 18%, and only two games (The Witcher 3 and Shadow of the Tomb Raider) were faster on AMD's GPU.
These results are reminiscent of our testing with AMD and Nvidia's desktop equivalents, where AMD performs better at lower resolutions, thanks to RDNA2's higher core frequencies and large Infinity Cache. Still, overall performance was in favor of the 3080 at all three resolutions.
Strange Behavior
Jarrod notes the RX 6850M XT's behavior is very strange. In previous testing with the RX 6800M and RTX 3080 — in different laptops, not with Asus' XG mobile devices — he found performance to be nearly equivalent between the two GPUs in gaming workloads, with both discrete GPU options having 150W power limits.
This situation is compounded by system power draw for the Asus' Flow X13 and XG mobile, which was significantly higher when using the RX 6850M XT. Total System power peaked at 171W with the RTX 3080 XG mobile connected but jumped to 235W when the RX 6850M XT enclosure was used, a 37% increase in power consumption.
We've seen AMD's older RX 6800M go toe-to-toe with Nvidia's RTX 3080 mobile graphics while consuming roughly the same amount of power. It now remains a mystery as to why the RX 6850M XT is so inefficient.
Spec for spec, the RX 6850M XT only features minor upgrades from the 6800M (hence the reason it's not called a 6900M). Memory capacity and core count remain identical between the two SKUs, with the only difference being a 163MHz increase to GPU frequency for the RX 6850M XT, and a 2 Gbps uptick in memory speed for the GDDR6 modules which now run at 18Gbps. That could account for some of the power increase, but probably not all of it.
For now, it's best to take these results with a dose of salt, as the RX 6850M XT's poor performance could be the result of Asus' unusual configuration involving its external GPU enclosures. Hopefully, more laptops can be tested soon with the RX 6850M XT built into them to see how the GPU performs in a typical laptop form factor.
