For our temperature testing, we measure the peak memory temperature under load. A reading under load comes from running Metro Exodus Enhanced Edition for 30 minutes.
The same can be said for the memory thermals, with both BIOS modes producing a peak temperature of 66C. This is good enough, though perhaps not jaw-droppingly good – but then again, there's no practical benefit to the GDDR6X to run any cooler, so it almost doesn't matter.