I have the Gigabyte z390 Aorus Pro-CF motherboard. I currently have a 512 Gig NVMe drive in it, and I have room to add a second one which I’d like to do since Amazon has the Prime sale. But I thought I’d remembered that adding a second NVMe drive might impact video card performance because of some kind of shared PCI bus type thing? The only thing I see mentioned is it would cut off some of my SATA drives, so that’s be a pain as I’ll have to figure out something for those drives. Arghh.
On z390s in general, the GPU(s) will use PCI Express Lanes from the CPU itself, while all other PCI-E devices (including NVMe drives, since the m.2 slots are treated as such internally) run off the lanes from the chipset. Two high-end NVMes might impact each other’s performance, but shouldn’t bother your video card.
edit: your manual, on pg. 20, also goes into how the two NVMe slots can impact availability of SATA ports (which share some lanes due to the same limitation mentioned above), if you have a ton of older HDDs or optical drives or what-have-you.
It looks like I’ll need to slot in a PCIe SATA card for my older SATA drives. Will that hurt my video card performance if it’s not being used most of the time? Like my most intensive games and stuff will be on the NVMe drives
If it’s not on the x16 or x8 slots, based on my reading, it should still be pulling from the chipset’s lanes, rather than the CPUs, so it also shouldn’t affect GPU performance.
edit: it’s also fair to note here that limitations possible in these scenarios are pretty unlikely. The amount of bandwidth that these two sets of lanes can manage is pretty absurd for general use, even in fairly high-end gaming. If you’re continuously maxing out two upper-echelon SSDs while streaming a ton of data via a PCI-E wifi card, you could potentially see performance impacts on those write/read operations, but for the average non-workstation application, you’re gonna be okay.