I've had success on X79!
So, I wanted to document my success on an unsupported platform. Big shout out to UNOE who gave me a push in the right direction.
So I have a Rampage IV Extreme with a 512GB Samsung 950 Pro. I used this PCI-E adapter to get it working (but I don't think it's very adapter specific at all)
http://www.amazon.com/gp/product/B01798WOJ0/
At first the 950 Pro didn't show up under my boot devices in my BIOS. I was a bit worried that I would have to modify my BIOS, but it turns out that all I had to do was let my BIOS initialize all drives and eventually it came up fine. I originally loaded the default config in my BIOS and that showed me my 950 Pro. I have the most up-to-date BIOS for my Rampage IV Extreme if that makes a difference. I saw some people say they saw the device as "PATA" but mine didn't specify.
I put NvmExpressDxe-64.efi into my "drivers64UEFI" folder. You can do this by installing Clover to a random USB flash drive with the "BiosblockIO" setting enabled and make sure to install "NvmExpressDxe-64" under the drivers64 section. After that move the file from drivers64 on your flash drive to drivers64UEFI folder on your boot device.
Then I placed NVMeGeneric.kext into my relevant kext folder (10.11 for me). I'd suggest against placing it elsewhere, or in two places at once. It could potentially cause issues loading it up.
Also make sure you have the boot flag "usekernelcache=no" in your clover config.plist. I've noticed issues with root device if that is not enabled. Your boot might be a bit longer, but being able to boot at all I think takes precedence, haha.
Also if you are cloning your old install to an NVMe drive, make sure you disable TRIM before you clone it! Having TRIM enabled could potentially cause booting issues. Personally I wasn't able to clone my drive over successfully, so I made a fresh install and it worked right away.
When booting, it's important you choose the "UEFI OS" 'drive' when booting. Choosing my 950 Pro itself won't boot. Kind of odd that it shows up as UEFI OS instead of just appending [UEFI] in front of the drive name.
Here is a picture I took with my phone at first boot.
Really hope this helps other people out! It took me all day to get it working, so I figured I'd share what worked for me.
For those who can't get the above working and have an unsupported chipset/mobo, you might need to modify your BIOS to get it working. It should work for all 6-series mobos and up. Check this thread out
http://www.win-raid.com/t871f16-Gui...for-Intel-Chipset-systems-from-Series-up.html