Bit of an update regarding using the riser. Annoyingly, the way my Motherboard (MPGx570 Gaming carbon) has it's PCIE lanes configured is causing me problems.
CPU controlled
PCI_E1
M2_1
Chipset controlled
PCI_E2, E3, E4
M2_2
I have an MP600 in the M2_1 Slot and an MP510 in the M2_Slot. If I restrict the CPU lanes to PCIE 3 to allow my riser to work, I lose performance on the MP600. Admittedly I'd barely notice in real world currently but why compromise.
It looks like I'll need to buy a PCIE 4 riser card or take a relook at the Motherboard. I was planning on upgrading from a 3700x to the 3950 Zen3 equivalent and given the MPGx570 gaming has VRM temp issues, it may be worth upgrading.