GeForce RTX 3000 graphics cards were the first to receive the latest GDDR6X memory from Micron. This memory is rated to run at up to 21 GHz, but even in the RTX 3090 it runs at 19.5 GHz. It looks like we now know what the reason is.
A source specialist ran RTX 3080 tests and found that the hottest memory chip warmed up to a very impressive 104 degrees. Despite the fact that Micron has stopped specifying temperatures for its memory chips since the days of GDDR5, this is a very high temperature anyway. According to certain data, for GDDR6X, the temperature of 120 degrees is probably considered critical, and the maximum operating temperature can lie in the range of 105-110 degrees. That is, in the RTX 3080, the memory can warm up to the maximum permissible temperatures for it, and this is not very good. Probably, increasing the frequency to 21 GHz would lead to even more heating and throttling, which in this case is also possible.
It should be noted that 104 degrees is precisely the maximum temperature, but it is impossible to find out on which microcircuit it was reached. Combining this data with the IR photograph of the board, we can conclude that we are talking about one or several microcircuits located to the right of the GPU near the elements of the board’s power subsystem. Elsewhere, the ICs seem to be about 20 degrees cooler.