For our temperature testing, we measure the peak GPU core temperature under load. A reading under load comes from running Cyberpunk 2077 for 30 minutes.
As for thermals, in the out of the box state, there is very little to split between the Twin X2 and the Founders Edition. The Inno3D came in with a peak of 61.4C on the GPU, and 74.1C on the hot spot, making it roughly 1C cooler than Nvidia's own design. There's very little in it though, so let's see if noise levels will separate these two cards…