Available SATA ports on GA-Z170X-Gaming GT?

[boyscout]

A pair of Samsung 950 PRO 512gb SSD (under RAID 1) are installed in the two M.2 positions.  That affects the availability of the SATA ports, understood.  However we seem to have fewer than expected.

BIOS is set to RAID.  Following the charts on pg 32 of the manual, we installed a pair of Sandisk Extreme Pro 960 SSD on ports 4 and 5, RAID 1, works fine.  An Intel 240gb SSD and LG optical drive are installed on ports 6 and 7, works fine.

Thought we still had two available SATA ports (#1 lower left and #2 lower right) but an older pair of 600gb Western Digital conventional drives installed on those ports are ignored by BIOS and Windows 10.

Should ports 1 and 2 be available or have I been staring at those charts too much?

Thanks in advance for advice.

[joevt]

Doesn't that chart say that only port 4 is available? 6 and 7 are not handled by the Intel chipset so they are always available.

I'm looking at the RAID mode chart for M2D_32G M.2 connector, PCIe x4 SSD because the Samsung 950 Pros are not SATA, they are PCIe 3.0 x4 NVMe. There's an "x" (meaning not supported) at position SATA3_0, 1, 2, 3, 5. But that doesn't explain why port 5 is working for you... Even if you look at the non-RAID mode chart for M2D_32G M.2 connector, PCIE x4 SSD, then it shows port 4 and 5 are available.

[boyscout]

I've been reading the charts backwards. You're saying that the SSD types listed down the left side of the charts are related to the SSDs *in the M.2 slots*.  I'm a newb... I was reading them as types of devices I could - or could not - plug into SATA ports 0-5, which led me to the conclusion that I could put ordinary SATA drives on all but ports 0 and 3.   

Mysteriously, as reported a pair of Sandisk drives are plugged into ports 4 & 5 even though 5 should not be working.  The BIOS identifies both correctly in their positions, puts them under RAID 1 without complaint, and Windows 10 sees a single drive (as it would under RAID) that seems to be working fine.  Is it possible that despite all appearances the system is only using the drive in port 4?  How to test that?

Any recommendations for a controller that will live happily in this system (only one video card, two slots free) and provide more SATA ports?  The ports would be for HDD and optical only, PCIe x1 type probably OK? 

Thanks.

[joevt]

You might try testing port 4 and 5 with different drives that are not raided while keeping the RAID setting in BIOS.

Use google to find a controller and/or check the usual online stores. I can only find PCIe 2.0 x1 SATA cards. That would max out at 500 MB/s. That would be good enough for mechanical drives or one SSD (even if you had two SSD's you probably would be accessing only one at a time). A PCIe 3.0 x1 SATA card would be preferable at 985 MB/s but all the PCIe 3.0 SATA cards appear to be x8 which would be overkill. You could use the x8 slot but that would make your graphics card x8 also but maybe you won't notice the difference.

There's probably an Intel chipset manual that explains the options in more detail, but just trying the ports should be good enough.