I have a very big case (5 x 5.25 and 5x 3.5 slots).
What I am now realizing is that I do NOT want to have the m.2 in pcie to take awy sata ports, but I don't care if it steals from any of the PCIe3.0x16 lanes. I really don't need the PCI3 3.0x16 because I am not running big GUI cards. I will just use the onboard GUI on the CPU chip. I have read that there are some MBs that borrow the lanes from the PCIe3.0x16 and not from the SATA ports. However, most of the MBs seem to take away one or even 2 of the Sata ports.
I run 5 Sata HDs and want to keep them. So finding a MB that will have M.2 in pcie mode that will NOT steal away any of the SATA ports is most important.
The problem is that the ASUS and ASRock websites do not always make it perfectly clear where the m.2 steals from. Even downloading the pdf manuals does not always make it clear if the m.2 borrows/steals the SATA or the PCI3 lanes.
I would even get a more expensive MB with extra PCIe3.0x16 slots, because I would not need them for anything other than using the m.2 to take their lanes.
Still, thanks for all the help. The more I read, the more confusing it gets, but also the more I am learning about these new z370 MBs.
Thanks again for all the help.
C2
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EDIT: I just realized that I would be able to add a SIIG M.2 NGFF SSD PCIe Card Adapter in one of the PCIe slots which would allow the use of the M.2 M key pcie card. This would add the M.2 without taking away any SATA lanes. Now I can focus more on a Z390 MB with the best overall stability and other features. Thanks again for the help you guys have given; You really do help so much! ]]