QwerkyPengwen :
to clarify on the sata port usage:
unless the motherboard specifcally supports PCIe connectivity through the M.2 slot it will use up 2 of your SATA ports on your motherboard in order to get the speeds that the SSD supports. Typically if your motherboard is saying it'll use 2 of the sata ports then that means your board doesn't have any 6Gb/s SATA slots and only has 3Gb/s SATA slots and M.2 SSD's need 6Gb/s so it uses 2 of your slots to get it.
Can't get any specs on the board that you have that specifically states it uses 2 of your SATA ports instead of 1 port. Also can't get any specs that tell me what speed those ports run at, but it's SATAIII so it should be 6Gb/s and the M.2 should only use one of them. The specs I looked at also don't say that it supports PCIe connectivity for the M.2 so I would assume it uses the SATA.
Now let's gear ourselves toward some questions for you.
You say that you have a standard HDD as well as two SSD's. What are all of those drives used for and what are their sizes, also, which drive is your boot drive? is it one of the two SSD's? what size is it? what else do you put on it? If it's possible to move stuff around to get you the space you need for the OS and it's updates then that's what we'll do. Or, if it's one of those drives and all you use it for is solely the OS and it's extremely small then perhaps consider just getting a bigger one to replace it and just unplug one of your disk drives to make room for it so that you can use a cloning software to simply clone your current boot drive over to it and start booting from that one with no loss in files or having to wait to do a fresh install and do updates and whatnot.
my boot drive is 111 gb, the HDD is a 931 gb drive, and I have a 894 gb ssd, both non boot drives are used for steam libraries, emulators, and other apps, however, I'd like to upgrade to a faster drive so windows doesn't feel like an eternity to update and load, and coworkers have raved about M.2 being lightning fast, plus I am not doing the install myself as I have a friend who can take care of the cloning software.
looking at the user guide, the M.2 slot is supporting PCIe 3.0 x4 and SATA 6gb/s standards, 4.2cm/6cm/8cm length m.2 cards
also supports PCIe 3.0 x4 NVMe Mini SAS SSD with turbo U.2 Host card* *sold separately