Yeah, it’s not pretty. The Radeon RX 6800 pretty much gets massacred in this test. It’s slower than even the last-gen GeForce RTX 2080 Ti by quite a bit and more than half as much compared to the RTX 3080. I reckon this has to do with AMD’s hybrid approach to ray-tracing where the BVH traversal is done by the shaders, while the RA units only handle the ray-box and ray-triangle tests.
NVIDIA’s RTX GPUs offload the entire RT workload to the RT cores and can concurrently run both pipelines without one affecting the other. I’m guessing the shader pipeline is stalled when AMD offloads the shader code for ray-tracing to the SIMDs.
One interesting observation I made with the ray-tracing test was that the in-game frequency dropped to just 2000MHz, all the way from 2.45-2.5GHz in rasterized titles. This could either be the result of excessive power consumption, or simply an example of the overhead penalty due to the use of shaders for BVH traversal. Read more here:
Overclocking the Radeon RX 6800: A Lot of Untapped Potential
The Radeon RX 6800 has a surprising amount of overclocking headroom. We were able to push it to as much as 2.55GHz, with rock-solid stability. There isn’t much room to increase the power and voltage, but we maxed them out. The memory was a bust. We started running into crashing even on adding just +50 to the memory offset. This is something we saw with the RDNA 1 parts as well, so it’s nothing new:
The overclocked results are quite impressive. The Radeon RX 6800 manages to nearly level with the RTX 3080 in roughly half of the games we tested, while reducing the deltas to ~8-10% in the rest. Compared to the RTX 3070, the overclocked RX 6800 is approximately 35% faster, with certain titles such as Tomb Raider seeing gains in excess of 40%. Unfortunately for NVIDIA, the RTX 3070/3080 comes with little to no overclocking headroom.
Smart Access Memory (SAM)
Unfortunately, on our system, we had a rather disappointing experience with SAM. Out of the seven games we tested, only two showed an observable gain upon turning SAM (or resizeable BAR). Far Cry 5 and SOTTR gained 2 and 3 FPS, respectively on average while the lows also improved. This is still within the margin of error, and unless I see otherwise, SAM is still just a marketing term with no significant real-world consequences.
Conclusion: Budget 4K with some Caveats
The Radeon RX 6800 is a decent product overall, but the pricing will make many mainstream gamers think twice before they make their decision. The stock performance is slightly faster or a notable step up compared to the cheaper RTX 3070, depending on the resolution you play at. At 1440p, you’re only looking at marginal gains, but the 4K performance is quite impressive, holding a lead of 25-30% over the 3070, even catching up to the RTX 3080 upon overclocking.