NFSU

Not quite, I believe that if it's an M.2 SSD (thin-looking), then it'll use your motherboard (Chipset's) PCIe lanes, whereas, your CPU PCIe lanes will be used for GPU. The blue encirclement on this image shows where the M.2 would be slotted https://gyazo.com/13f0fd70b6664223035da76bed31279a , although you may already know this, I like to be thorough with answers Ignore the orange encirclement 
 
Short answer: It'll be fine Your GPU won't be affected by the installation of an M.2 PCIe Gen3 SSD 

Make sure you dont have any Spydows 10 updates in your "to install" updates.
Just google the name for any KB*Number* update to verfiy what it does.
 
Once you've done that, you probably want to reset windows update, google for "windows update reset", several ways to do that and they are not all equal.
So you have to trial & error a bit here.
 
Run CCLeaner aswell as Windows own DiskCleanup on your C: drive and delete w/e you deem unnecessary or could be windows update releated.
 
If all of these fail, you probably will have to reformat or hope that a later update fixes that issue you are having.

It'll work.

Lower CL is better. That's a type of latency - the lower the value, the lesser the delay. They'll probably work totally fine.

You can read in my signature what I think of 980s everything else is fine except the motherboard. You can't use a 2600 in a z97 mobo. You need a motherboard with the LGA 1155 socket, but z97 uses the LGA 1150 socket. You need a p67, z68 or z77 motherboard to get the most out of your cpu. Those aren't in production anymore, so you need to look on e-bay or amazon for leftovers. z77 is the best of the 3, but either one will do.