AMD Big Navi, RX 6000, Navi 2x, RDNA 2. Whatever the name, AMD's next-generation GPUs are promising big performance and efficiency gains, along with feature parity with Nvidia in terms of ray tracing support. Will Team Red finally take the pole position in our GPU hierarchy and lay claim to the crown for the best graphics card, or will the Nvidia Ampere architecture cards keep the top spots? It's too soon to say, but here's everything we know about AMD Big Navi, including the RDNA 2 architecture, specifications, performance, release date and pricing.
With Nvidia's GeForce RTX 3090, GeForce RTX 3080, and GeForce RTX 3070 now revealed, and the first two officially launched, the ball is in AMD's court. There are various ways of looking at the Nvidia Ampere launch. It's Nvidia doing its best to bury AMD before Big Navi even steps out the door, or Nvidia is scared of what AMD is doing with RDNA 2, or Nvidia rushed the launch to get ahead of the holiday shopping spree, or ... you get the point. The RTX 3080 and 3070 appear to be priced reasonably (relative to the Turing launch at least), and demand right now is very high. Frankly, AMD would have likely benefitted if it could have launched Big Navi already, but it has a lot of other balls it's juggling (like Zen 3).
AMD has now officially unveiled Big Navi, including specs for the RX 6900 XT, RTX 6800 XT, and RTX 6800. We've updated our expectations below with the latest information, though there are still future RDNA2 products yet to be revealed. Based on what we've seen, Big Navi may finally put AMD's high graphics card power consumption behind it. Nvidia's RTX 30-series cards leave plenty of room for AMD to catch up, considering the 3080 and 3090 have the highest Nvidia TDPs for single GPUs ever. Let's start at the top, with the new RDNA 2 architecture that powers RX 6000 / Big Navi / Navi 2x. Here’s what we know, expect, and occasionally guess for the AMD's upcoming GPUs.
Big Navi / RDNA 2 at a Glance
- Up to 80 CUs / 5120 shaders
- 50% better performance per watt
- Coming November 18 (RX 6800 series), December 8 (RX 6900 XT)
- Pricing of $579, $640 and $999 for RX 6800, RX 6800 XT and RX 6900 XT
The RDNA 2 Architecture in Big Navi
Every generation of GPUs is built from a core architecture, and each architecture offers improvements over the previous generation. It's an iterative and additive process that never really ends. AMD's GCN architecture went from first generation for its HD 7000 cards in 2012 up through fifth gen in the Vega and Radeon VII cards in 2017-2019. The RDNA architecture that powers the RX 5000 series of AMD GPUs arrived in mid 2019, bringing major improvements to efficiency and overall performance. RDNA 2 looks to double down on those improvements in late 2020.
First, a quick recap of RDNA 1 is in order. The biggest changes with RDNA 1 over GCN involve a redistribution of resources and a change in how instructions are handled. In some ways, RDNA doesn't appear to be all that different from GCN. The instruction set is the same, but how those instructions are dispatched and executed has been improved. RDNA also adds working support for primitive shaders, something present in the Vega GCN architecture that never got turned on due to complications.
Perhaps the most noteworthy update is that the wavefronts—the core unit of work that gets executed—have been changed from being 64 threads wide with four SIMD16 execution units, to being 32 threads wide with a single SIMD32 execution unit. SIMD stands for Single Instruction, Multiple Data; it's a vector processing element that optimizes workloads where the same instruction needs to be run on large chunks of data, which is common in graphics workloads.
This matching of the wavefront size to the SIMD size helps improve efficiency. GCN issued one instruction per wave every four cycles; RDNA issues an instruction every cycle. GCN used a wavefront of 64 threads (work items); RDNA supports 32- and 64-thread wavefronts. GCN has a Compute Unit (CU) with 64 GPU cores, 4 TMUs (Texture Mapping Units) and memory access logic. RDNA implements a new Workgroup Processor (WGP) that consists of two CUs, with each CU still providing the same 64 GPU cores and 4 TMUs plus memory access logic.
How much do these changes matter when it comes to actual performance and efficiency? It's perhaps best illustrated by looking at the Radeon VII, AMD's last GCN GPU, and comparing it with the RX 5700 XT. Radeon VII has 60 CUs, 3840 GPU cores, 16GB of HBM2 memory with 1 TBps of bandwidth, a GPU clock speed of up to 1750 MHz, and a theoretical peak performance rating of 13.8 TFLOPS. The RX 5700 XT has 40 CUs, 2560 GPU cores, 8GB of GDDR6 memory with 448 GBps of bandwidth, and clocks at up to 1905 MHz with peak performance of 9.75 TFLOPS.
On paper, Radeon VII looks like it should come out with an easy victory. In practice, across a dozen games that we've tested, the RX 5700 XT is slightly faster at 1080p gaming and slightly slower at 1440p. Only at 4K is the Radeon VII able to manage a 7% lead, helped no doubt by its memory bandwidth. Overall, the Radeon VII only has a 1-2% performance advantage, but it uses 300W compared to the RX 5700 XT's 225W.
In short, AMD is able to deliver roughly the same performance as the previous generation, with a third fewer cores, less than half the memory bandwidth and using 25% less power. That's a very impressive showing, and while TSMC's 7nm FinFET manufacturing process certainly warrants some of the credit (especially in regards to power), the performance uplift is mostly thanks to the RDNA architecture.
That's a lot of RDNA discussion, but it's important because RDNA 2 appears to carry over all of that, with two major new additions. First is support for ray tracing, Variable Rate Shading (VRS), and everything else that's part of the DirectX 12 Ultimate spec. The other big addition is, literally, big: a 128MB Infinity Cache that will help optimize memory bandwidth and latency.
There will certainly be other tweaks to the architecture, but AMD is making some big claims about Big Navi / RDNA 2 / Navi 2x when it comes to performance per watt. Specifically, AMD says RDNA 2 will offer 50% more performance per watt than RDNA 1, which is frankly a huge jump—the same large jump RDNA 1 saw relative to GCN.
It means RDNA 2 could deliver either the same performance while using 33% less power, or 50% higher performance with the same power, or most likely some in between solution with higher performance and lower power requirements. It looks like AMD is doing a bit of both, as TBP (Total Board Power) is 300W for the 6900 XT and 6800 XT, and 250W for the RX 6800. Part of the PPW improvements come thanks to the Infinity Cache, which we'll discuss more below.
The one thing we know for certain is that RDNA 2 / Big Navi / RX 6000 GPUs will all support ray tracing. That will bring AMD up to feature parity with Nvidia. There was some question as to whether AMD would use the same BVH approach to ray tracing calculations as Nvidia, and with the PlayStation 5 and Xbox Series X announcements out of the way, the answer appears to be yes.
If you're not familiar with the term BVH, it stands for Bounding Volume Hierarchy and is used to efficiently find ray and triangle intersections; you can read more about it in our discussion of Nvidia's Turing architecture and its ray tracing algorithm. While AMD didn't provide much detail on its BVH hardware, BVH as a core aspect of ray tracing was definitely mentioned, and we heard similar talk about ray tracing and BVH with the VulkanRT and DirectX 12 Ultimate announcements.
AMD's RDNA 2 chips will contain one Ray Accelerator per CU, which is similar to what Nvidia has done with it's RT cores. Even though AMD sort of takes the same approach as Nvidia, the comparison between AMD and Nvidia isn't clear cut. Nvidia for example says it roughly doubled the performance of its RT cores in Ampere. AMD says the Ray Accelerator does ray-triangle intersection calculations about 10 times faster than a software (shader) solution. That suggests Big Navi RT performance might not match Ampere, as on paper at least it looks similar to Turing RT performance.
The Infinity Cache is perhaps the most interesting change. By including a whopping 128MB cache (L3, maybe L4?), AMD should be able to keep basically all of the framebuffer cached, along with the z-buffer and the most recent textures. That will dramatically reduce memory bandwidth use and latency, and AMD claims the Infinity Cache allows the relatively tame GDDR6 16 Gbps memory to deliver an effective bandwidth that's 2.17 times higher than the raw numbers would suggest.
The Infinity Cache may also help a lot with ray tracing calculations. We've seen on Nvidia's GPUs that memory bandwidth can impact RT performance on the lower tier cards like the RTX 2060, but it might also be memory latency that's to blame. AMD hasn't revealed RT performance yet, not with any actual benchmarks, but it could go either way. AMD might be sandbagging, or it might only deliver modest RT performance. We'll know more in the coming weeks once we get our hands on the hardware.
One thing we don't know about the Infinity Cache is how that will propagate down to the lower tier RDNA2 chips. 128MB is very large, and based on AMD's image of the die, it's about 17 percent of the total die area on Navi 21. The CUs by comparison are only about 31 percent of the die area, with memory controllers, texture units, video controllers, video encoder/decoder hardware, and other elements taking up the rest of the chip. Navi 22 and Navi 23 will have far lower CU counts, which means a 128MB cache would occupy even more of the die space. Most likely, the Infinity Cache will either be cut down in size to 64MB (maybe 96MB or 32MB or some other value), or on the budget parts it might be removed completely. We'll have to wait and see what AMD does, but a smaller size is the most likely approach.
It's worth noting that Nvidia also has Tensor cores in its Turing architecture, which are used for deep learning and AI computations, as well as DLSS (Deep Learning Super Sampling), which has now been generalized with DLSS 2.0 (and DLSS 2.1) to improve performance and image quality and make it easier for games to implement DLSS. So far, AMD has said nothing about RDNA 2 / Navi 2x including Tensor cores, though it mentioned an upcoming Super Resolution feature that may be mostly equivalent to DLSS. AMD's CAS (Contrast Aware Sharpening) and RIS (Radeon Image Sharpening) already overlap with DLSS in some ways, and Super Resolution will be part of the open FidelityFX suite, so we'll have to wait and see how it compares against DLSS. Even without Tensor cores, it may be possible to do all the inference side of a DLSS-style algorithm using the FP16 capabilities of Navi 2x.
AMD is planning multiple Navi 2x products, and we expect to see extreme, high-end and mainstream options—though the latter are likely coming later, given RX 5500 XT and RX 5600 XT aren't that old. AMD will release the highest performance options first, eventually following up with mid-range and budget solutions.
RX 6000 / Big Navi / Navi 2x Specifications
What does all of this mean for RX 6000 / Big Navi / RDNA 2 desktop GPUs? If you thought the Xbox Series X GPU sounded potent, what with its 52 CUs, Big Navi is taking things a step further. AMD is basically doubling down on Navi 10 when it comes to CUs and shaders, shoving twice the number of both into the largest Navi 21 GPU.
Navi 10 is relatively small at just 251mm square, and while AMD didn't reveal an official die size yet, AMD has used much larger die sizes in the past. After months of rumors and speculation, we can finally shed some light on the full specs for the top three Big Navi GPUs.
|Graphics Card||RX 6900 XT||RX 6800 XT||RX 6800||RX 6700 XT?||RX 6500 XT?|
|GPU||Navi 21 XTX||Navi 21 XT||Navi 21 XL||Navi 22?||Navi 23?|
|Die size (mm^2)||536? (#salt)||536?||536?||?||236?|
|Max Clock (MHz)||2250||2250||2105||2100?||2100?|
|VRAM Speed (MT/s)||16000||16000||16000||14000?||14000?|
|Infinity Cache (MB)||128||128||128||?||?|
|Launch Date||Dec 8, 2020||Nov 18, 2020||Nov 18, 2020||Jan 2021?||Jan 2021?|
The highest spec parts all use the same Navi 21 GPU, just with differing numbers of enabled functional units. Navi 21 has 80 CUs and 5120 GPU cores, and is reportedly more than double the size (536mm square) of the current Navi 10 used in the RX 5700 XT. But a big chip means lower yields, so AMD has parts with 72 and 60 CUs as well.
While AMD hasn't confirmed this, one recent rumor is that RX 6900 XT will only be sold initially as a direct-from-AMD GPU. That would make some sense, as yields of fully functional Navi 21 chips are likely to be quite low. Disable 8 CUs and yields will jump significantly, while with 20 CUs disabled probably most of the chips in a wafer will be viable options. Anyway, the RX 6900 XT gets the full chip, RX 6800 XT has 72 CUs and will be the main launch part, and the RX 6800 is the third Navi 21 variant with 60 CUs.
Big Navi / RDNA 2 adds support for ray tracing and some other tech, which should require quite a few transistors. The very large Infinity Cache is also going to use up a huge amount of die area, but it also helps overcome potential bandwidth limitations caused by the somewhat narrow 256-bit bus width on Navi 21. Note that Nvidia has opted for a 320-bit bus on the 3080 and 384-bit on the 3090, plus faster GDDR6X memory, so Nvidia has much higher raw bandwidth, but it comes at the cost of higher power requirements.
There are still some unknown factors. AMD hasn't yet provided a deep dive into the RDNA 2 architecture, so there may be other changes that will help AMD compete with Nvidia. Clock speeds on the other hand are the highest boost clocks we've seen to date, which come thanks to optimizations and data path updates that AMD has put into the design. Still, it's worth pointing out that the Game Clock (which tends to be similar to Nvidia's Boost Clock) is only around 2GHz, and Nvidia is getting pretty close to that same speed with the various Ampere GPUs. That's interesting, as generally speaking TSMC's N7 process is superior to Samsung's 8N (revised 10nm) that Nvidia's using for Ampere.
Getting back to the memory side of things, AMD's configurations are going to be very interesting to see in practice. 16GB of GDDR6 for the top three cards is great to see, and it means memory capacity at least won't be a problem. The memory bandwidth does look pretty weak, but again that Infinity Cache could go a long way toward alleviating demands on the GDDR6 memory. If AMD's 117% improvement in effective bandwidth claims prove accurate, even with 512 GBps, the Navi 21 GPUs will behave like they have over 1 TBps, relative to Nvidia's cards. That's more than even the RTX 3090.
There are two other Navi 2x cards listed where we still don't have official specs. We've filled in the blanks with the latest rumors, but as with all rumors, take them with a scoop of salt. RX 6700 XT looks like it will carry on from the current RX 5700 XT at the $400 price point, and the RX 6500 XT (there's apparently no RX 6600 XT, at least so far) will take over from the RX 5600 XT. We don't expect either of these to launch until 2021, and they may not come out until March or even April.
As far as a true budget Navi 2x card is concerned, no one is posting any real information on that yet. There will might be a Navi 24 or something in the coming year, with only 20-30 CUs max. That would put it at the level of the Xbox Series S, at which point we're not sure if it's worth including ray tracing support. We'll have to see how things develop in the coming months, though, as 1080p with Super Resolution upscaling might run fine on such a GPU.
Big Navi / Navi 2x Performance Expectations
With the official reveal now complete, we have AMD's internal performance metrics as a reference point. All of the testing was done with an as-yet-unreleased Ryzen 9 5900X CPU, and of course AMD could skew things in its favor. Still, the specs and relative performance look entirely feasible.
At the top, the RX 6900 XT will go up against RTX 3090. AMD definitely skews things in its favor here, enabling the new Smart Memory Access feature and also running with the one-click Rage Mode overclocking enabled. Even then, performance looks maybe comparable to the 3090. Of course, AMD also costs $500 less, but when we're looking at $1000 graphics cards such things don't matter quite as much. Anyone with the money to pay for the absolute best will probably still go with Nvidia, getting access to DLSS and other extras that AMD doesn't offer.
Stepping down to the RX 6800 XT and RTX 3080, things get quite a bit more heated in the matchup. AMD's figures seem to give it a slight performance advantage, and it costs $50 less and uses a bit less power as well. The RTX 3070 and RX 6800 swings even further in AMD's favor, with an apparently lead of 10-15 percent for AMD on average.
More important than price and performance right now is going to be availability, however. Whoever can ship more GPUs in the next month or two will come out ahead, and Nvidia of course has a two month lead over AMD in that respect.
Big Navi / Navi 2x Graphics Card Model Names
AMD has said it will launch a whole series of Navi 2x GPUs. The Navi 1x family consists of RX 5700 XT, RX 5700, RX 5600 XT, and RX 5500 XT (in 4GB and 8GB models), along with RX 5600/5500/5300 models for the OEM market that lack the XT suffix. The RX 6000 series so far consists of just three options, but more will come.
AMD could simply add 1000 points to the current models, but there are a few changes this round. At the top, the 6900 and 6800 models don't have any direct previous equivalent. Below those, however, AMD hasn't announced any actual cards. That leaves us with new performance and pricing tiers with the RX 6900 XT, RTX 6800 XT, and RX 6800. We expect RX 6700 XT, RX 6500 XT, and other cards to show up next year.
There's still a 200 point gap between the high-end 6700 XT and the mainstream/budget 6500 XT, according to the latest rumors. But then, the rumors could be wrong so we'll just have to wait and see how things develop.
RX 6000 / Big Navi / RDNA 2 Release Date
AMD reiterated many times that RDNA 2, aka Big Navi, would launch in 2021. That's set to take place on November 18 for the RX 6800 XT and RX 6800, and December 8 for the RX 6900 XT. What we don't know is how many cards will actually be available for purchase. (We don't know how many Nvidia Ampere GPUs have been sold either, for the record.)
The impact of COVID-19 around the globe continues to be a problem, and AMD has lots of pies cooking right now. Besides Big Navi, there's the new Ryzen 5000 CPUs, Xbox Series X and Xbox Series S, and PlayStation 5. All of the chips are manufactured using TSMC's N7 node, which is perhaps why Nvidia ended up at Samsung for the consumer Ampere GPUs.
Regardless, supply likely won't be sufficient to meet the demand from gamers and enthusiasts, even on extreme parts like the RX 6900 XT. Just like Nvidia's Ampere GPUs, we expect AMD to sell everything it produces for at least the rest of 2020. Hopefully come 2021 things will calm down a bit, and we'll have enough GPUs to go around. And less pandemic mayhem (knock on wood).
RX 6000 / Big Navi / Navi 2x Cost
It's not too surprising that AMD's RX 6000 GPUs are targeting higher prices than the previous generation. Even the RX 6800 costs $579, which is more than any of the previous RX series GPUs. (Only the Radeon VII cost more.) The RX 6900 XT meanwhile goes for a cool grand, a price we haven't seen from any AMD graphics card since the dual-GPU HD 7990 back in 2013 (though the R9 295X2 still holds the record for AMD pricing at $1499).
Our earlier estimated pricing ended up being a bit too ambitious, but then we didn't really expect AMD to match Nvidia's RTX 30-series performance. But when you can play with the best, you expect people to pay for the best. AMD comes in well below Nvidia's pricing on the RTX 3090, and slightly below the RTX 3080 pricing as well. Meanwhile, RX 6800 costs slightly more than the RTX 3070.
We don't know exactly how the various GPUs perform yet, which is obviously a big factor. Nvidia has been doing RTX hardware and DLSS for two years now, and there's at least some benefit in that. Use of DLSS in particular is starting to pick up, and we definitely appreciate the option to boost performance with very little change in image fidelity. If performance is the same in apples-to-apples benchmark comparisons, paying a bit more for Nvidia isn't out of the question.
Considering the large 500mm square or larger die size, the cost of TSMC's N7 lithography, and the 16GB VRAM on the models AMD has officially revealed, the pricing looks pretty reasonable. There are already situations where 8GB VRAM can be a bit of a handicap, and the RTX 3070 is going to struggle or have to drop settings a notch. In short, AMD has competitive GPUs coming that appear to go toe to toe with Nvidia, and just like it's doing with Zen 3 CPUs now that it appears to have a clear lead over Intel, AMD is raising its prices and ditching — or at least deemphasizing — the value proposition.
It's still worth noting that traditionally, AMD GPUs tend to drop below MSRP much more quickly than Nvidia GPUs. We almost certainly won't see that happen in 2020, but 2021 it wouldn't be too surprising to see sub-$500 RX 6800. Nvidia can drop prices as well, so that's something to watch for once supply improves.
Big Navi and RX 6000 Closing Thoughts
AMD has a lot riding on Big Navi, RDNA 2, and the Radeon RX 6000 series. After playing second fiddle to Nvidia for the past several generations, AMD is ready to take its shot. AMD has a lot to prove outside of PC graphics cards, though. RDNA 2 is the GPU architecture that powers the next generation of consoles, which tend to have much longer shelf lives than PC graphics cards. Look at the PS4 and Xbox One: both launched in late 2013 and are still in use today.
The current performance slides from AMD are promising, but we're particularly interested in finding out how Big Navi performs with ray tracing. Higher performance in games that don't use ray tracing might be more important today, but a year or two down to road, that could change. Then again, the consoles have AMD GPUs and are more likely to see AMD-specific optimizations, so either way AMD looks to be in a good position.
Nvidia left the door open for AMD to walk through, and Team Red is on the march. In a few weeks, we'll see just how well the various GPUs handle real-world independent gaming tests. We'll also see if AMD can claim the best CPU for gaming crown with Ryzen 5000. It's been a long time since AMD was able to rank at the top for both CPUs and GPUs, not since the early days of the Athlon 64 have we seen such a thing.
Just as important as performance and price, though, we hope AMD can avoid the shortages that have plagued Nvidia's RTX 3080 and 3090 cards. Part of that comes from demand for new levels of performance, and every Ampere GPU purchase prior to Big Navi's launch means one less buyer for AMD. Still, there's only so much silicon to go around. Samsung apparently can't keep up with demand for Ampere GPUs, and TSMC has a lot more going on — it can only produce so many N7 wafers per month! Like Ampere, we'll probably see Big Navi shortages until early 2021 at least.
Without actual hardware in hand, running actual gaming benchmarks, we can't declare a victor. Still, these last few months of 2020 are shaping up to be very exciting in the GPU world, which is good as the first part of 2020 sucked. Considering it's been more than a year since AMD's Navi architecture launched, we're definitely ready for the next-gen GPUs.