Asus Prime Z270-A with two m.2 SSD

[Adorjan_B]

I got a little bit confused by the ports, and I would like to know, if I could place two Samsung m.2 SSDs in the motherboard while they are both at full possible power. And how many more Sata ports will I have avaiable for HDD use after I put the two m.2s in? I think it's 2? Maybe?

 

[Jwpanz]

Do you have the motherboard and the manual?

 

[raisonjohn]

I got a little bit confused by the ports, and I would like to know, if I could place two Samsung m.2 SSDs in the motherboard while they are both at full possible power. And how many more Sata ports will I have avaiable for HDD use after I put the two m.2s in? I think it's 2? Maybe?

It depends on the type of M.2 SSD you will use (if it's SATA-based only *or* if it is NVMe supporting PCIe speeds).

Yes, your Asus Prime Z270-A motherboard does have two (2x) M.2 sockets for your Samsung M.2 SSDs:
The bottom M.2 socket (below the chipset) is the M.2_1 that supports both SATA-based and PCIe-based M.2 SSDs.
The top M.2 socket (just above the GPU slot) is the M.2_2 which only supports PCIe-based M.2 SSDs.

Assuming you will be using Samsung NVMe M.2 SSDs supporting PCIe x4 speeds (such as the Samsung 960 EVO), if your plug the SSD on the M.2_1 (i.e., the bottom socket), make sure to go to BIOS (under Onboard Devices Configuration) and check if M.2_1 Configuration is in [PCIE Mode]. This will ensure the PCIe-based SSD will run in faster PCIe x4 speeds (not slower SATA speeds). If it is incorrectly set in [SATA Mode], your PCIe-based M.2 SSD might only run in SATA speeds (or not at all) and will result in disabling of one of your SATA ports (i.e., SATA6G_1).

If you plug the PCIe-based SSD on the M.2_2 (i.e., the top socket), make sure to go to the same BIOS menu as above and check if M.2_2 Configuration is in [X4]. This will ensure the SSD run in full PCIe x4 speeds (not at slower x2 speeds). Note that using [X4] will disable two of your SATA ports (i.e., SATA6G_5 and SATA6G_6). If it is incorrectly set in [X2], the PCIe-based SSD will only run in PCIe x2 speeds, but enables the two SATA ports mentioned.

So, in short, when you plug in two NVMe/PCIe-based Samsung M.2 SSDs on both M.2 sockets of your motherboard, and set the M.2_1 socket in [PCIE Mode] and the M.2_2 socket in [X4], you will be left with four SATA ports available (SATA6G_1, SATA6G_2, SATA6G_3 and SATA6G_4).

Source: http://dlcdnet.asus.com/pub/ASUS/mb/LGA1151/PRIME_Z270-A/E12294_PRIME_Z270-A_UM_V2_WEB.pdf?_ga=2.6527344.397344019.1502131710-1428616915.1495995095