This is a real
good point. Luckily, I do have a full PCI-E 3.0 x16 port as my current 2.5GbE card is stuck there.
I was thinking of adding an additional SAS card (in IT mode so I can connect more SATA drives) so I have to check how many lanes are needed for it. My Mini-ITX mainboard has only that one x16 PCI-E slot and additional M.2 port that could be converted to x4 slot, if I got it right.
SAS card I found is with 8 ports and it's PCIe 2.0 x8. Some other cards with 4 ports are using PCI-e 2.0 x4. I would definitely have to do some PCI lane calculations
What I would try is to add a SAS card to x16 slot and 533FLR-T to x4 slot (if that is what comes out of M.2 riser) and test if it would work because I need only one working port.
Also wandering how much is this card gonna increase the idle power consumption (if it's that hot) from current 30-35W.