The HP Quickspecs document says slots 4, 5 and 3 in order of preference but no explanation of why.
The HP Installation manual says slots 4 and 5 only.
I would like to move it to slot 3 from slot 4, assuming that slot 4 supports "PCIe port bifurcation " but bifurcation is separate issue that I need to research.
I have the 512GB Z Turbo Drive G2 installed in slot 4 as the boot drive, as it came from HP.