Here we present the average clock speed for each graphics card while running the 3DMark Time Spy stress test for 30 minutes. We use GPU-Z to record the GPU core frequency during the Time Spy runs. We calculate the average core frequency during the 30 minute run to present here.
Clock speeds from the RTX 3070 Founders Edition are very healthy, and about as stable as we'd expect from a modern Nvidia GPU. The frequency starts off high, peaking at 1950MHz, but settles down after about 3-4 minutes as temperature climbs, and spends the remainder of the stress test just below 1900MHz, with the occasional spike up to 1920MHz.
Taken across the 30 minute run, the GPU averaged 1885MHz, well above the rated boost clock of 1725MHz.