Both the top M.2_1 and bottom M.2_2 sockets can operate in either SATA or PCIe mode. Enable PCIeX4 mode for the The top socket where your 960pro NVMe drive is and use the bottom socket for your M.2 SATA SSD just leave the setting for M.2_2 as is, it defaults to SATA when inserting a SATA M.2 SSD. You will be fine. The 960Pro will use PCIe lanes at X4 and the 860evo M.2 will use SATA.

The PCIeX options present for M.2_2 are for when one wants to use a second NVMe drive in M.2_2 and wants to enable PCIeX mode. In that scenario one might run into bottle necking though, as the M.2 sockets both are getting and utilizing their PCIe lanes from the chipset.

Though honestly IMO, it's more cost effective to use a 2.5" SATA SSD for additional storage unless you are out of mounting options or (and I can appreciate this) just don't want to run any more cables for power and data to keep things clean and tidy looking.

Hey Moreluck,

1. You should install your 860 EVO with it being SATA, on the M.2_1 port (for PCIe 3.0 x4 & SATA)
2. Move your 960 PRO to the M.2_2 Port (for PCIe 3.0 X4 ONLY)

Disable the following SATA ports from BIOS:
SATA Port 1 - For M.2_1 operating in SATA Mode
SATA Port 5 & SATA Port 6 - For M.2_2 operating in PCIe 3.0 X4

+rep if it works and let me know if your 960 PRO's speeds are downed.

SherardG you won’t lose data if you do this will you? *Got a NIB Hero X for $99 on eBay (sealed and everything) and installed windows etc on 970 pro on M.2_1 first, installed older 960 pro on M.2_2 however ASUS will not recognize it. Plugged and unplugged, double checked that it’s seated, nothing. Sorta afraid to take the 2_1 off and put it on the 2_2 and something happen.*

Anyone have advice for the M.2_2 drive issue?*