The spec sheet says the 30mm slot has 2 pci lanes, so I’m taking that to mean the primary has 4, and is therefore faster? I’ll be ordering in the next week or so and would rather not install Windows twice, though maybe I can use WinPE and CrystalDiskMark to check before installing.
short M.2 slot is porbably 2 lanes yes, while long M.2 SSD slot runs on 4 lanes. If that is what you mean?
usualy you would install on long M.2 SSD anyway since it is standard one and comes with bigger storage etc. i currently have a PCIe GEN 4 installed in my FW 16 since that is max GEN it has as default support. You can use GEN 5 but it will simply run on GEN 4 speeds and interface than GEN 5.
I have 2 Corsair p310s sitting in my desk at work, waiting for my order to be placed & arrive. A 2 and a 4. So probably use the 2 for media and split the 4 into 1 (boot) and 3 (data/games)