Does X370 Professional Gaming support 4x8Gb£

Dear Ricardo,
This has got nothing to do with the board, the memory controller is integrated in the CPU, and runs optimnal at 3200MHz
https://www.amd.com/en/product/8446
Using 3600 or above, doesn't do anything for the overall performance, unless the latency timing is lower, which usually it isn't, higher clock speeds, often can only work with higher latency timing which is slower in performance, only a synthetic memory benchmark, will show better results, but the CPU will not go any faster.
The reason why it istn't working, is that there are only 2 true memory manufacturers, to my knowledge only Samsung and Crucial produce their own PCB's en memory chips.
The rest are assemblers, who buy PCB's and chips, from companies like Hynix, Elpida, Nanya, Samsung, Spectek, Micron and others.
And since introduction of DDR4 there is a huge shortage of chips, so these assemblers buy anything they can lay their hands on.
Problem is the fact that they keep re-using the same partnumber, as long as size, speed and primary timing are the same.
So one day you buy a kit with 512MB Hynix chips on it, next day the same partnumber contains 1GB chips, from another brand, and I have seen people who bought 2 kits in 1 purchase, and both kits had different chips
Memory these days is a silicon lottery
You have 2 working kits, but the chips on these kits simply do not match, and the board cannot find a setting, it can start with.
If I were you, I would return the second kit, and sell the first kit, and go for a 2x 16GB DDR4 3200 or 1600MHz, and I know for a fact that Patriot Viper, usually works on every board.
It is better to use 2 modules, since the memory controller only works in dual channel, and there is no advantage in using 4 modules, also sometimes, 4 modules can only run at lower speeds.
Best slots are A2 B2