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Sapphire RX 7900 XTX Nitro+ Vapor-X Overclocking
Overclocking of AMD's new RX 7900 cards is a bit unusual, in that the maximum boost clock is often set far higher than anything you'll ever achieve in practice. The reference 7900 XTX for example has a 3115 MHz boost clock, but typically runs in the 2.5–2.6 GHz range. Increasing the boost clock to 3300 MHz (or more) does basically nothing, as the GPU is smart enough that it never even tries for those higher clocks.
With the Sapphire RX 7900 XTX Vapor-X, the factory stock boost clock is actually slightly lower than on AMD's reference card: 2970 MHz. You can increase that to something higher, but it mostly goes unused. Increasing the power limit can do more for performance than adjusting the boost clock.
We used our normal trial and error process to attempt to dial in a stable overclock. Since the GPU clock didn't matter much, we just maxed out the power limit at 115% and set the GPU for 3100 MHz, and then attempted to find a stable memory overclock. The chips are officially rated for 20 Gbps ("2498 MHz" in Afterburner), but there's usually a fair amount of headroom, and we ultimately settled on a "2750 MHz" setting, which equates to a 22 Gbps memory speed.
Peak power draw spiked at over 600W during a FurMark stress test at these settings, while gaming showed a maximum power use of up to 550W. Average power use was quite a bit lower, just under 500W, but this is basically within spitting distance of the RTX 4090. At stock, both peak and average power use dropped by around 65W. In short, you don't want to run this sort of card on an insufficient PSU, and 1000W or higher models (perhaps one of the best power supplies) are a good idea considering the high transients.
Fine tuning of voltages using AMD's Radeon Settings could result in better figures, but for these tests we stopped here and set about benchmarking at 4K ultra in our test suite. You'll find the overclocked numbers from the 7900 series cards in the charts in green.
Sapphire RX 7900 XTX Test Setup
We updated our GPU test PC and gaming suite in early 2022, but with the RTX 40-series launch, we found more and more games were becoming CPU limited at anything below 4K. As such, we've upgraded our GPU test system again.
We're including the performance results for the RTX 4070 Ti in the charts, along with the reference 7900 XTX/XT, RTX 4080/4090, and the previous generation RTX 3090 Ti and RX 6950 XT. We used the latest AMD and Nvidia drivers available at the time of testing: 22.12.2 for the 7900 series, 22.11.2 for other AMD GPUs; 527.62 for the Nvidia GPUs.
Since this is a third-party custom card, we're only testing at 1440p and 4K in our gaming suite. Results in professional applications and at 1080p can be found in our initial RX 7900 XTX and XT review.
TOM'S HARDWARE INTEL 13TH GEN PC
Intel Core i9-13900K
MSI MEG Z790 Ace DDR5
G.Skill Trident Z5 2x16GB DDR5-6600 CL34
Sabrent Rocket 4 Plus-G 4TB
be quiet! 1500W Dark Power Pro 12
Cooler Master PL360 Flux
Windows 11 Pro 64-bit
OTHER GRAPHICS CARDS
AMD RX 7900 XTX
AMD RX 7900 XT
AMD RX 6950 XT
Nvidia RTX 4090
Nvidia RTX 4080
Nvidia RTX 4070 Ti
Nvidia RTX 3090 Ti
AMD and Nvidia both recommend either the AMD Ryzen 9 7950X or Intel Core i9-13900K to get the most out of their new graphics cards, and for the third party cards we're going to stick with the 13900K. (The Ryzen 9 7950X provided similar performance on the reference 7900 cards.) MSI provided the Z790 DDR5 motherboard, G.Skill got the nod on memory, and Sabrent was good enough to send over a beefy 4TB SSD — which we promptly filled to about half its total capacity. The be quiet! 1500W PSU is ATX 3.0 compliant and 80 Plus Titanium certified.
We also have Nvidia PCAT v2 (Power Capture and Analysis Tool) hardware that allows us to capture the real-time power use, GPU clocks, and more during all of our gaming benchmarks. We'll have the results on the power testing page.
For all of our testing, we've run the latest Windows 11 updates. Our gaming tests now consist of a standard suite of nine games without ray tracing enabled (even if the game supports it), and a separate ray tracing suite of six games that all use multiple RT effects.
We've tested the Sapphire and other GPUs at 4K and 1440p, using "ultra" settings — basically the highest supported preset if there is one, and in some cases maxing out all the other settings for good measure (except for MSAA or super sampling). We've also hooked our test PCs up to the Samsung Odyssey Neo G8 32, one of the best gaming monitors around, just so we could fully experience some of the higher frame rates that might be available — with FreeSync enabled.
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