M.2 SSD PCIe recommendation/compatibility with motherboard?

Since the motherboard manual and specifications do not state this, there is something very important you need to find out.

call gigabyte, ask them if the m.2 is using pcie x2 or x4 and if one of their bios updates support the use of nvme. you will not get good speeds off of x2. you can use the pcie bus. z97 came out right around when they were staring to update boards with x4. my z97 oc formula unfortunately has x2..