I'm unfamiliar with PCIe SSDs but i'm aware they are much faster in read/write.
The motherboard i'm thinking about buying is CALLED Gigabyte GA-X99-UD4P, Socket-2011-3 and the PCIe SSD i'd like is called Samsung 950 PRO 256GB M.2 PCIe SSD.
The motherboard says it supports M.2, but i've read up that booting from this SSD could be problematic. Will it be able to do this without buying extra parts? If yes/no, how can you tell? How will i know to check for this in the future. What will i have to do once i've assembled my computer to install and boot windows on this SSD?

Thank you so much for reading.

-Even from NorwayFor a desktop build, I would just got with a standard SATA type SSD. As far as PCIE SSD's my experience with them has been in some laptops where you can add one to have 2 drives whereas it only has a single SATA drive bay. You might run into troubles with the PCIE SSD, whereas the SATA SSD is an easy install. If your getting your parts from a good store you could RETURN them if you run into problems. To me a SATA SSD is fast enough, the slight performance gain in the PCIE SSD card to me isnt worth paying the extra premium for it. Good points by DaveLembke.
Also, doing a boot from SSD is fast, but only gives slight performance boost.
For better load times for programs, they must be on the SSD also.
Here is a link:
http://www.tomshardware.com/forum/284233-32-worth-boot-drive
Thee is some confusion as to what the SSD can do for your speed.
Here are some this it can NOT do.
 - Speed up the Internet
 - Speed  up the Hard Drive
 - Speed up the RAN
 - Speed up he CPU.

Why do I say this? Some users report HAT the SSD
 - speeds up everything.  Which is not true.
Of course, you can  decide for yourself. Or not.
You could experiment for the best performance. Or not.

With SSD, old proverb is true:
Beater to have than not have. 

 Thanks for the answers, I've just ordered both parts and more for my build after reading a lot up on both items and -how-to- instal PCIe SSD M.2, if i'm not terribly wrong in my research there won't be a compatibility issue, and i'll be able to use the hardware to its potential. There shouldn't be any compatibility issues, at most you'll need a BIOS update if your BIOS is quite out of date.
If you're planning on using Windows 7, there's some additional work required - with Windows 8/8.1/10, it's plug and play.  Let me know if you're planning to use Windows 7 and I'll provide more detail.

Source: Almost identical board and PCI-E SSD.  Oh, one thing to be aware of is that your board's M.2 slot is not "full speed" - you won't notice the difference in day-to-day use, but if it bothers you, consider buying an M.2 - PCI-E adapter, Lycom make a pretty cheap one.  This just basically lets you plug the M." drive into a spare PCI-E slot to get full speed.  Hope this makes sense, a little short on time right now but I can expand on this later if you'd like more info