AMD RX 6800 XT review

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After years focused on the budget and mid-range graphics card space, AMD has finally stepped up its game to challenge Nvidia's dominance at the high end with its RX 6000 series graphics cards. At the heart of the line-up is the RX 6800 XT, a 4K-focused powerhouse that competes with Nvidia's RTX 3080 on both price and performance.

There's a lot to like about the RX 6800 XT, from its top-notch gaming performance to the many exciting new technologies it supports. As impressive as it is though, it doesn't quite escape Nvidia's shadow. Significantly better ray-tracing performance and the wizardry that is DLSS let Nvidia maintain its lead, but it's a lead that's a lot smaller than it has been in a long, long time.

Tested on PowerCube gaming PC

• CPU: AMD Ryzen 7 5800X
• Motherboard: MSI MAG X570 Tomahawk Wi-Fi AM4 ATX
• RAM: 32GB Corsair Vengeance RGB Pro DDR4 3200MHz
• SSD Storage: 1TB Samsung 970 EVO M.2 NVMe SSD
• HDD Storage: 2TB Seagate Barracuda 7200RPM HDD
• CPU Cooler: Cooler Master ML240R RGB
• PSU: be quiet! Pure Power 11 700W
• Case: Tecware VXR Dual Chamber Mid Tower

Design

Design

• Priced and specced in between the RTX 3070 and RTX 3080
• 2.5 slot width requires a roomy case
• Axial fan cooling is a welcome improvement over the old blower design

The RX 6800 XT sits in the middle of the first wave of AMD's RX 6000 series graphics cards. It packs more power than the vanilla RX 6800 but less than the RX 6900 XT. Unsurprisingly, its pricing reflects this, with an MSRP of $1,049 compared to $949 for the RX 6800 and a cool $1,599 for the RX 6900 XT. It's a similar story when comparing the RX 6800 XT to Nvidia's top-end RTX 30 series graphics cards. $1,049 places the RX 6800 XT between the RTX 3070 with its $809 MSRP and the RTX 3080 with its $1,139 MSRP.

This hierarchy persists when comparing specs, though that might not be immediately apparent. The RX 6800 XT boasts a core clock speed of up to 2.015GHz and a Boost clock speed of up to 2.25GHz. Nvidia's cards might seem to lag behind here, with the RTX 3070 featuring core/Boost clock speeds of 1.5GHz/1.73GHz and the RTX 3080 coming in at 1.44GHz/1.71GHz.

But clock speeds can be misleading. Higher clocks don't always translate to better performance. The more relevant number to look at here is single-precision compute performance, measured in FLOPs (floating point operations per second). Floating point operations are one of the most common calculations in graphical applications, providing a useful benchmark for comparing the power of two or more graphics cards.

Despite its considerably higher clock speeds, the RX 6800 XT only just edges out the RTX 3070 with single-precision compute performance of 20.74 TFLOPs compared to 20.3 TFLOPs. The RTX 3080 trumps both, hitting a peak of 29.8 TFLOPs.

There's more to the memory specs than first meets the eye, too. The RX 6800 XT looks to have a significant advantage, boasting 16GB of VRAM compared to 8GB on the RTX 3070 and 10GB on the RTX 3080. It's a fair comparison with the RTX 3070, as both cards feature GDDR6 VRAM and a 256-bit memory bus. The RX 6800 XT comes out on top with its 16Gbps memory speed as well, topping the RTX 3070's 14Gbps.

The RTX 3080 comparison is a little more complicated. While it too features less memory than the RX 6800 XT, it uses faster GDDR6X VRAM with a wider 320-bit memory bus, enabling much higher memory speeds of 19Gbps. Since there are very few games that actually use 10GB of VRAM (much less 16GB), the faster speeds give the RTX 3080 the edge here.

For an AMD graphics card, the RX 6800 XT is quite power-hungry. AMD rates its typical power draw at 300W, recommending a PSU of at least 750W in your PC. In reality, I never saw the card draw down more than 275W, and I had no trouble running it off a 700W PSU.

Once again, this places the RX 6800 XT in the middle of Nvidia's cards. The RTX 3070 has a typical power draw of 220W and a 650W recommended PSU, while the RTX 3080 hits 320W and matches the 750W recommended PSU of the RX 6800 XT. Both the RTX 3080 and RX 6800 XT require two 8-pin connectors to supply power while the RTX 3070 needs just one.

AMD's reference board for the RX 6800 XT is a big 'un, taking up 2.5 slots and measuring at 267mm in length. Nvidia's reference boards are slimmer dual-slot affairs, with the RTX 3070 a shorter 242mm and the RTX 3080 stretching out to a lengthy 285mm.

In a departure from previous generations of AMD graphics cards, the RX 6800 XT reference board features a fan-based cooling solution. The "blower" cooling solution of old is gone, replaced with three axial fans that are quieter and more efficient at dissipating heat. This design change more closely aligns the reference board with third-party graphics cards as well as Nvidia's reference boards for its RTX 30 series.

Connectivity on the RX 6800 XT reference board is pretty standard fare. You've got two DisplayPort 1.4 ports, a single HDMI 2.1 port and a USB-C port.

Features

Features

• Infinity Cache is a crafty way of increasing effective memory bandwidth
• Smart Access Memory can boost performance significantly in certain cases
• Ray-tracing on AMD cards, finally!

For its RX 6000 series graphics cards, AMD has developed a new version of its RDNA architecture, appropriately dubbed RDNA 2. Along with support for a slew of new technologies, RDNA 2 promises significant performance improvements over its predecessor. According to AMD, the 6800 XT and its RDNA 2 architecture delivers up to 54% more performance per watt over the RX 5700 XT and its first-generation RDNA architecture. A lot of those performance gains stem from the RX 6800 XT's more-powerful components, but there are a few new technologies that play a role as well.

Infinity Cache

First up is the Infinity Cache. Located on the GPU die, the Infinity Cache consists of 128MB of high-speed memory with significantly higher bandwidth than the RX 6800 XT's 16GB of regular GDDR6 VRAM. Frequently-accessed data is automatically cached in this high-speed memory, drastically increasing the speed at which subsequent data requests can be satisfied. This results in what AMD claims is up to 3.25 times the effective bandwidth of the GDDR6 VRAM alone. At its peak, it even tops the access speeds of the 384-bit GDDR6X within Nvidia's RTX 3090.

However, it's important to note that the performance gains with Infinity Cache aren't universal. While the tech doesn't require any additional work from game or application developers, its impact depends on how often data is re-used. A game that makes repeated requests to a small pool of assets will likely see more significant improvements than a game cycling through a larger, more-diverse range of assets.

Smart Access Memory

The other big performance-boosting feature of RDNA 2 is AMD's Smart Access Memory (SAM) technology. Available exclusively to folks who have a PC with both a Ryzen 5000 series CPU and an RX 6000 series graphics card, SAM lets the CPU access the entirety of the GPU's VRAM at full speed, rather than being limited to a small portion of it as in most PC set-ups.

Forza Horizon 4 saw significant performance gains when enabling Smart Access Memory.

This enables faster data transfer speeds between the CPU and GPU, translating to considerable performance increases in certain circumstances. AMD cites a number of games that benefit from the tech, with the likes of Forza Horizon 4, World of Warcraft: Shadowlands and Assassin's Creed Valhalla receiving bumps of up to 12% to their FPS at 4K Ultra.

Of course, AMD's figures are very much best-case scenarios. In my testing, most games exhibited little to no improvement with SAM enabled. The one exception was Forza Horizon 4 where the average FPS jumped by 20% at 1080p Ultra, with 1440p and 4K experiencing lesser but still significant performance boosts.

It's early days for SAM, and it's possible that future games will be built in such a way to take better advantage of the faster CPU-to-GPU pipeline. For now though, meaningful performance gains are few and far between.

Ray-tracing

Perhaps the most highly-anticipated RDNA 2 feature is the arrival of hardware-accelerated ray-tracing. Two years after Nvidia introduced the tech in its RTX 20 series graphics cards, AMD has finally brought its own solution to the table, adding dedicated Ray Accelerator hardware to each compute unit of its RX 6000 series graphics cards.

By performing ray-tracing computations at the hardware level, the RX 6800 XT is capable of rendering real-time lighting, reflections and shadows much more efficiently than through a software-based solution. Not efficiently enough, however, to challenge Nvidia's more mature ray-tracing technology. RTX cards like the RTX 3070 and RTX 3080 deliver considerably better ray-tracing performance, even without the FPS boost enabled by Nvidia's impressive Deep Learning Super Sampling (DLSS) tech. Compatibility is an issue, too, with the pool of games supporting AMD ray-tracing dramatically smaller than those supporting Nvidia's RTX technology.

For this generation of graphics cards at least, Nvidia remains the dominant force in real-time ray-tracing.

Control is one of a select few games that supports ray-tracing on both AMD and Nvidia graphics cards.

DirectX 12 Ultimate

Beyond AMD's own tech, RDNA 2 adds compatibility with Microsoft's DirectX 12 Ultimate graphics API. As the API is still quite young, the list of supported games is pretty short. Nevertheless, there's a lot to get excited about as more developers take advantage of the features DirectX 12 Ultimate offers.

Among those features is DirectX Raytracing (DXR). DirectX 12 Ultimate updates DXR to version 1.1, improving ray-tracing performance in supported games. This is crucial for AMD, since it needs all the help it can get to catch up to Nvidia's superior ray-tracing implementation.

New to DirectX 12 Ultimate is Variable Rate Shading (VRS). This technology allows developers to adjust the rate at which different areas of a scene are updated. A game could, for instance, adjust the shading rate of areas that don't change dramatically from frame to frame such as the sky or the ground. Re-shading these areas less frequently often has little to no noticeable impact from a visual perspective, but it can offer considerable boosts to a game's performance.

Mesh Shaders are another DirectX 12 Ultimate feature with the potential for significant performance gains. With Mesh Shaders, developers can better leverage the parallel rendering capabilities of the GPU, leading to a faster and more efficient rendering pipeline.

While there aren't really any games that take advantage of Mesh Shaders yet, 3DMark's benchmarking software includes a Mesh Shader test to highlight the potential of the tech. Running the benchmark on the RX 6800 XT saw an average framerate of 31.03fps with Mesh Shaders off and 528.17fps with Mesh Shaders on, a 1,602% difference. That's seriously impressive, but remember that it's a test designed explicitly to highlight the power of Mesh Shaders and likely does not reflect the performance improvements we'll see when games start implementing the technology.

DirectX 12 Ultimate promises even more efficiency with its Sampler Feedback feature. This provides a game or application with more-detailed information regarding textures and how to optimally load them into memory. With this information, textures can be streamed in and out more efficiently, allowing for a smoother experience travelling through large open worlds.

The last and most enigmatic feature of DirectX 12 Ultimate is DirectStorage. Due for release some time in 2021, DirectStorage is an API that promises to deliver shorter load times and higher asset fidelity through optimisations to data streaming. It does this by reducing the overhead involved in requesting data as well as enabling batch processing of requests that better aligns with the modern GPU pipeline.

To deliver its promised performance improvements, DirectStorage will require an NVMe SSD drive – SATA SSDs and mechanical HDDs will not be supported.

Performance

Performance

• Great performance at 4K and 1440p
• Struggles to compete with Nvidia when ray-tracing is involved
• Thermals remain stable even under heavy load

As one of the most-expensive consumer-level graphics cards currently on the market, the RX 6800 XT should deliver top-tier performance across the board. It mostly does, sustaining smooth framerates at 4K and pushing 100+ FPS at 1440p to make the most of high-refresh-rate monitors. Turn on ray-tracing, however, and the RX 6800 XT stumbles hard.

Check out the charts below for a more-detailed breakdown of the RX 6800 XT's performance. I ran all the tests with the "Rage Mode" tuning preset in AMD's Radeon Adrenalin software, a feature exclusive to the RX 6800 XT and RX 6900 XT. Rage Mode gives the card more power to work with and turns up the fans to compensate for the additional heat generated, allowing it to sustain its Boost clock speeds for longer periods.

High performance 4K gaming is what the RX 6800 XT promises, and that's what it delivers. It happily hit an average of 60fps at 4K Ultra settings in all but two of the games I tested: Chernobylite and Control. Since Chernobylite is still in Early Access and Control taxes any GPU you throw at it, the lower performance in both titles is easy enough to overlook.

With the means to hit upwards of 100fps on average in games like Forza Horizon 4 and Wolfenstein Youngblood, the RX 6800 XT has a lot to offer folks building a 4K-focused gaming rig.

If you favour high refresh rates over sharper resolutions, the RX 6800 XT is just as compelling. It averaged in excess of 100fps at 1440p Ultra in all the games I tested excluding Control and Chernobylite, and even then it only fell short by a few frames per second. Performance showcases Forza Horizon 4 and Wolfenstein Youngblood managed to hold an average of more than 200fps, an impressive feat that makes the most of the increasingly-common 200Hz+ displays hitting the market.

Whether you're rocking a high refresh rate monitor or not, the RX 6800 XT delivers excellent 1440p performance.

At 1080p, the RX 6800 XT obliterated every game I threw at it. Maintaining an average of 120fps presented little challenge, with many of the games tested bumping up against CPU bottlenecks that kept them from hitting even higher framerates. If you've bought yourself a high-refresh-rate 1080p monitor, the RX 6800 XT will do it justice. For regular 60Hz displays though, it's pretty severe overkill.

Ray-tracing performance

There's no two ways about it: The RX 6800 XT struggles to deliver decent ray-tracing performance when compared with Nvidia's RTX cards. As one of only a handful of games that supports ray-tracing on both AMD and Nvidia cards, Remedy's Control highlights just how demanding the tech can be. At 4K, turning ray-tracing on and setting it to High saw the RX 6800 XT drop from an average of 46.94fps to just 18.38fps. Lowering ray-tracing to Medium lifted the average to 24.49fps, only a smidge above 50% of performance with ray-tracing turned off.

Only by dropping the resolution to 1440p does performance hit a decently-playable level. With ray-tracing set to High, the RX 6800 XT holds an average of 42.1fps with a minimum of 30fps – placing it roughly on par with the locked 30fps at 1440p that the Xbox Series X and PS5 deliver with ray-tracing turned on. No surprises there, given both consoles use custom AMD GPUs built off the same RDNA 2 architecture powering the RX 6800 XT.

Compared to Nvidia's RTX cards, these numbers are rough. Even without the massive performance boosts afforded by DLSS, the RTX 3070 and RTX 3080 leave the RX 6800 XT in the dust. Go back a generation and the RTX 2080 manages to match or exceed the RX 6800 XT in similar benchmarks.

To put it bluntly, if you want to experience ray-tracing as it's meant to be experienced, you'll be best served sticking with Nvidia.

AMD talks a big game with its Smart Access Memory (SAM) technology, promising performance gains of up to 16% for folks with both a Ryzen 5000 series CPU and RX 6000 series GPU in their PC. In reality, my testing showed that SAM's impact varies dramatically from game to game, with most titles showing little to no improvement with SAM enabled.

As you can see in the chart above, Forza Horizon 4 was the clear winner here. At 1080p, its average framerate leaped by more than 20% with SAM enabled. 1440p and 4K saw lesser but still significant improvements to their average framerates too.

Forza was very much an outlier, however. The rest of the tested games exhibited only minor gains, many of which could be attributed to the variability of real-time benchmarking – this would explain the performance drops some games experienced. Gears Tactics did enjoy a 7.3% increase to average framerate at 1080p, but that was the only other instance of notable improvement.

Interestingly, it's not just the individual game that impacts SAM performance. When running the same tests on the same PC with AMD's less-powerful RX 6800, I saw considerable divergence in many of the results. Most notable was Wolfenstein Youngblood, which saw average FPS go up by as much as 18.52% on the RX 6800 compared to just 2.14% on the RX 6800 XT. I suspect the game is bumping up against different bottlenecks at the higher framerates achieved by the RX 6800 XT, but it's hard to be certain.

Does SAM provide enough of a performance boost to warrant building an all-AMD system over one with Intel and Nvidia components? I'm leaning towards a "no", for now at least. It's possible that upcoming games may be built with awareness of technologies like Smart Access Memory in mind, allowing them to take advantage of the expanded CPU-to-GPU data channel to the extent that Forza Horizon 4 currently does. Until then, SAM is more of a nice-to-have than a killer feature.

Synthetic benchmarks

In-game performance is always a better measure of a graphics card's capabilities than a synthetic benchmark, but the latter does serve as a useful tool for comparing cards at a glance. As such, I ran the RX 6800 XT through the Time Spy and Port Royale tests included in popular benchmarking suite 3DMark.

The Time Spy test is a DirectX 12 benchmark focused on general graphical performance. The RX 6800 XT completed with a graphics score of 17,608. According to 3DMark's test database, this places it ahead of the average scores for both the RTX 3070 and RTX 3080 at 12,559 and 15,886 respectively.

However, in the Port Royal ray-tracing test, Nvidia's superior RTX technology streaks ahead. With a score of 9,037, the RX 6800 XT edges out the RTX 3070's average score of 8,255 but lags far behind the RTX 3080's average score of 11,527. As with the Control benchmarks above, this further reinforces how much work AMD's ray-tracing solution needs before it can compete with Nvidia.

Thermal performance

AMD graphics cards have traditionally emphasised thermal efficiency, requiring less power and producing less heat than their Nvidia counterparts. With the shift in focus towards high-end performance, the RX 6000 series isn't quite as conservative as its predecessors, but the results are impressive nonetheless.

Despite AMD rating its typical power draw at 300W, the RX 6800 XT never exceeded 275W in my testing. It had no trouble running off my test PC's 700W PSU either, despite AMD recommending a PSU with 750W of power.

Temperatures remained relatively cool as well. Under load, the RX 6800 XT recorded an average of 70.5 degrees Celsius, topping out at 76 degrees when running more demanding games like Control at 4K. These temperatures are quite a bit hotter than the RX 6800 which averaged 62.81 degrees under load and maxed out at 71 degrees. Nevertheless, they're well within safe thresholds and provide a good bit of headroom should you want to overclock the card to squeeze out more performance.

Should you buy the AMD RX 6800 XT?

After years of sitting on the sidelines as Nvidia dominated the high-end graphics card space, AMD is finally giving its competitor a run for its money. The RX 6800 XT goes toe-to-toe with the RTX 3080 in raw graphical performance, delivering excellent performance at 4K and 1440p even in the latest, most demanding games. Factor in the promising Infinity Cache and Smart Access Memory tech, and you have plenty of compelling reasons to consider AMD over Nvidia for your new PC build.

That said, Nvidia still has a significant edge over AMD in hardware-based ray-tracing. The RX 6800 XT struggles to match the ray-tracing performance of RTX 20 series graphics cards, much less the more-powerful RTX 30 series cards. Then there's Nvidia's incredible DLSS tech, capable of dramatically boosting the performance of RTX cards with minimal impact on visual quality. AMD still has no answer to DLSS, and it really needs one if it wants to remain competitive going forward.

Pricing and availability

Price

MSRP $1,049

Where to buy

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Specifications