Today, we have two RX 6700 XT cards. AMD's reference card comes with the base level of performance and a design that echoes the other RX 6000 reference cards. Physically, the 6700 XT has the length and width of the RX 6800, but it's slightly shorter and significantly lighter. It measures 267x110x38mm and weighs 883g, while the RX 6800 measures 267x120x38mm and weighs 1384g. The RX 6700 XT also uses a dual-fan configuration, but it has custom 88mm fans, whereas the 6800 has custom 78mm fans. Considering the similar power ratings, we'd expect the RX 6700 XT to run a bit hotter than the other RDNA2 cards, but we'll check the details below.
The other card we have comes from Sapphire, the RX 6700 XT Nitro+. Besides a modest factory overclock, the Sapphire card uses a much larger heatsink with triple fans. It measures 313x131x48mm, so it's a 2.5-slot width. Despite the large size, it only weighs 1020g — more than the reference card, but quite a bit less than the reference 6800 card. The two outer fans on the Nitro+ are custom 94mm diameters, while the center fan is a slightly smaller 83mm model (all measurements are mine, and could be off by about 1-2mm).
We'll have a separate write-up of the Sapphire card soon, and we'll include the performance results here as a point of reference for the various factory overclocked models that will likely be far more common than the reference design. We ran out of time during testing to do a full overclocking investigation, so the Sapphire card also stands in for those results. We'll also include performance results from a Gigabyte RTX 3060 Ti card in the charts to show how custom Nvidia cards stack up — and the Gigabyte card was tested with the latest 461.72 drivers, which mostly appears to have affected performance in Horizon Zero Dawn.
Software: FidelityFX, Radeon Boost, and More
The latest AMD and Nvidia drivers are packed full of features and options. For AMD, the latest enhancements include Anti-Lag, Radeon Boost, Image Sharpening, streaming options, and more. AMD also offers other software tools, like the FidelityFX library for developers, including CAS (Contrast Aware Sharpening), ambient occlusion, and screen space reflections. AMD's Super Resolution remains a work in progress and isn't available yet, unfortunately. All of the FidelityFX libraries are royalty-free and open source and work with any compatible graphics card, including Nvidia's cards.
Time constraints preclude us from testing every feature in the software options, and turning certain options on can impact our performance measurements. We ended up benchmarking using the "Standard" profile in AMD's drivers, which turns off all extras. We've also encountered bugs in the past (e.g., with Enhanced Sync) that sometimes make the extras more trouble than they're worth. Still, we appreciate having choices for tuning performance available.
As an example, Radeon Boost combines resolution scaling with CAS to improve performance. When you're moving, and particularly turning, most games have blur effects, and it's difficult to see all of the high quality details. At the same time, turning represents an action that can benefit from higher frame rates, as it often means you're trying to aim at an enemy. Radeon Boost lowers your rendering resolution in such situations to increase fps, and the loss in image fidelity shouldn't be very noticeable. Theoretically, it's the best of both worlds… but it doesn't work well for our apples-to-apples benchmarking.
There's a whole series of testing we can look at, including things like Radeon Boost, DLSS, Anti-Lag, Reflex, Chill, and more. We're looking at ways to quantify these features, but again: Time constraints. Our advice is to try some of these features and see if you like the result. If a feature potentially drops fps slightly but improves latency, that could be a net win. Or if a feature improves fps while causing a drop in image quality that you don't actually notice, that's another potential win. AMD and Nvidia both have a bunch of tech that's worth further investigation, but we'll focus on performance in like for like testing for this initial review.
We're interested in hearing your thoughts on what features matter most as well. We know AMD and Nvidia make plenty of noise about certain technologies, but we question how many people actually use the tech. If you have strong feelings for or against a particular tech, let us know in the comments section.
Our test hardware remains unchanged from previous reviews, but we have made a few updates. Specifically, we're now running the latest version of Windows 10 (20H2, build 19042.867), and we've also updated our motherboard BIOS to version 7B12v1B1, which includes beta resizable BAR support (aka, 'ReBAR').
AMD first brought attention to this existing feature of PCI Express with its RX 6800 series launch last November, dubbing it Smart Access Memory (SAM). At the time, AMD only supported the feature with the latest-generation Zen 3 CPUs, 500-series chipset motherboards, and AMD's latest RDNA2 GPUs. Since then, both Nvidia and Intel have begun supporting ReBAR as well, and AMD has extended support to other CPUs and GPUs. As a result, it's now possible for us to enable ReBAR on our primary test PC.
Speaking of which, we keep thinking it should be time to upgrade, but the gains from slightly faster CPUs aren't quite to the point where we've felt it was necessary to swap testbeds and retest everything. That's a daunting task. We looked at CPU scaling on the latest GPUs at the time of the RTX 3060 Ti launch, with a focus on the top-performing solutions (Ryzen 9 5900X, Core i9-10900K, and Core i9-9900K). While there were some differences, overall the net gain from swapping to a different CPU is only 1–2 percent, and the 9900K remains more than capable. Maybe we'll swap when the 11900K arrives later this month; more likely, waiting for Alder Lake or Zen 4 seems like a better plan.
We're using the same 13 games as well, but again with a change: Besides game patches, we've elected to drop DXR use in Dirt 5 and Watch Dogs Legion — sorry, ray tracing fans. There are several reasons for this. First, DXR support in Dirt 5 was provided via an early access code, and the support was and is still buggy. Second, the visual improvements from enabling ray tracing in these games are present, but they're not huge while the performance hit can be quite significant. Finally, we wanted to include AMD's previous-gen RX 5700 XT card in our test results, and it can't support DXR.
We'll be looking at a deeper investigation into the state of ray tracing in the coming days. It remains an interesting topic and it's not going away, but we felt it wasn't as critical a factor on the lower echelon cards. AMD's RT performance remains generally worse than Nvidia's RT performance, but some of that undoubtedly stems from Nvidia's position as the first company to provide DXR hardware and the 2-year lead it had on AMD. DLSS is something we would also need to factor into testing, and then we're back to comparing apples and AI-upscaled apples — not exactly unfair, but also not quite the same. So, stay tuned for a future article on the subject.
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