sate slotBecause if it has PCIe slots, I would just get a PCIe card to NVMe adaptor and use that until you can plug the drive into the new machine. Another solution would be puttingSo a gen4 drive in the 3.0SATA slot will be limited to gen3 speeds, as will a gen3 drive in the 4.0 slot. But either will work just fine. So if you get one 3.0 drive, mht as well put it in