The AMD Radeon RX 6800 XT is the best representation of the RDNA 2 inflection point that has accompanied the red team's latest gaming architecture. It's a high-end graphics card unlike really any we've seen from AMD in recent years, the RX 6800 XT is right on time, competitive, and without caveat when it comes to gaming performance in a wide range of modern games.
That's not to say AMD hasn't had some superb graphics cards in the past—the RX 480 stands out for its tremendous value proposition over the duration of its lengthy time with us. No, what I mean is that the RX 6800 XT is competitive at a level which AMD hasn't been able to reach for some time, and it does not require a generous helping of in-game optimisations from hard-pressed developers to get there.
The second generation of an architecture tailor-made for gaming, RDNA 2 is not just an incremental step towards high-end performance, but rather a staggering leap.
What was once only competitive with Nvidia's third-run GPUs, the RDNA architecture has come on drastically with only a single turn of the crank. It now sits provisionally alongside Nvidia's enthusiast class RTX 3080 and RTX 3090, and that's no simple feat.
So how did AMD play catch up? There's a lot to discuss when it comes to RDNA 2 and the RX 6800 XT. From Infinity Cache to Ray Accelerators, the Navi 21 die isn't without shiny new things to lure the avid PC gamer. But, perhaps most importantly, the RX 6800 XT is also a lesson in how dragging Intel kicking and screaming from its gaming throne offered more than just the know-how to make a decent CPU.
Let's just say that AMD has figured out a few techniques that don't go amiss whether you're aiming for an IPC increase with a brand new CPU or building out a more performant GPU.
AMD RDNA 2 architecture
AMD RDNA 2 architecture
With a continuation of the 7nm process, you'd be easily fooled into thinking that there's little to talk about when it comes to performance per watt and clock speed. RDNA 2 pulls no punches in either, offering 30 percent higher frequency for the same power draw as the previous generation, or 50 percent greater power savings while holding the same frequency.
That cross-pollination of ideas and methodologies between Zen and RDNA 2 starts here: In order to improve performance while retaining roughly the same process node, AMD has incorporated custom libraries, tools, methodologies, and structures used to build Ryzen 5000-series CPUs into RDNA 2 in order to run it at higher frequencies or the same frequencies for less power.
Those have clearly been successful. For a clear cut example of the initial power savings and 7nm optimisations, just look to the first-generation RDNA top dog: the RX 5700 XT. This first wave card delivers 40 CUs at 225W with a top clock of 1,905MHz. The RX 6900 XT doubles the CUs, all of which run up to 18 percent faster, for just 33.33 percent greater power.
To further help the architecture along AMD has built in further capacitance in alternating current (CAC) optimisations right down to the metal with RDNA 2. These optimisations go down to the very capacitance of transistors as they switch. It's all in order to ensure that a maximum benefit and power saving is being achieved at a transistor and clock level. From there, it's all about scaling up an architecture that just doesn't waste any juice.
At a base level you're already getting more performance out of the same components with RDNA 2, but that doesn't make for a lax approach on a uniquely architectural level. From here AMD's building out with an eye on maintaining a level of efficiency throughout, and not blowing the entire power budget on a 512-bit bus, I'm told.
AMD really wants people to know bandwidth is not all about bus width—forget what ya heard.
A 512-bit bus, AMD explains, is costly and large. Two things AMD of all companies knows it can't get away with. That's also why you'll not see HBM2 memory anywhere near RDNA 2's hallowed PCB either. Instead, AMD is incorporating a new concept with RDNA 2: Infinity Cache.
Infinity Cache is what you might call a cure-all for AMD's GPU issues of the past— its gaming panacea, so to speak. It's a close relation to Infinity Fabric, the interconnect used throughout Zen 2 and Zen