UPDATE (2022/12/06): A fresh set of AMD Radeon RX 7900 XTX scores emerged some time after the ones reported in the story. They draw a more accurate picture of the graphics card with an OpenCL score of 228,647 and Vulkan score of 179,579, putting it squarely between Nvidia's GeForce RTX 4090 and RTX 4080.
Original article (2022/12/05)
Apart from a few extrapolated graphs by the community, very little is known about how AMD's upcoming Radeon RX 7900 XTX and Radeon RX 7900 XT fare against Nvidia's Ada Lovelace behemoths. Pure rasterization performance between the two flagships could be as low as 10%, but Team Green will almost certainly have the upper hand in raytracing. Now, the Radeon RX 7900 XTX has shown up on Geekbench, and its showing is less than stellar.
In Geekbench's OpenCL test, the AMD Radeon RX 7900 XTX scores 150,372 points. It is lower than the last-gen Radeon RX 6900 XT's average score of 170,000 and miles behind the GeForce RTX 4090 (~350,000+). The situation is identical in the Vulkan benchmark, where the graphics card scores a paltry 91,652 points. One can chalk its abysmal performance down to unoptimized drivers. That said, the delta is a bit too much, so there could be other factors at play here.
One can safely rule out CPU/memory bottlenecks, as the test rig is specced out with an AMD Ryzen 9 7950X and 32 GB of DDR5 memory. An eagle-eyed Twitter user noted the Radeon RX 7900 XTX sample was running via a compatibility layer for Windows due to a lack of ROCm support. Geekbench isn't the best tool to test graphics cards, to begin with, and real-world benchmarks should begin to show up once its December 13 launch date approaches.