Here we present the average clock speed for each graphics card while running the 3DMark Fire Strike Ultra stress test for 30 minutes. We use GPU-Z to record the GPU core frequency during the Fire Strike Ultra runs. We calculate the average core frequency during the 30 minute run to present here.
The ASRock RX 5500 XT Challenger 8GB averaged 1828MHz under load, meaning it is 24MHz faster than the 4GB Sapphire Pulse model based on this testing. That is not much at all, so it means we can confidently say that where we saw performance margins of 5-8%, this must be due to the difference in VRAM capacity.
Typically, where memory limitation is not a factor, such a small difference in clock speed results in performance differences of just 1%, if not less. In the three games where the 8GB model outperformed the 4GB model by 5-8%, we have to attribute that to the memory capacities.