When I did the new clean install of Windows 10 on my XPS 9530, after applying the Samsung Magician software 4.6, i noticed that I could not enable RAPID mode because the software was unable to determine my OS Version.
I did some poking around and found this Microsoft forum posting about having the similar problem with Windows 10 Preview version.
Even though Windows 10 is out and legit, it doesn't look like Samsung is ready to release an update to its software that will fix this problem. The posting has instructions but if you rather save time reading
[Back out Samsung Magician 4.6 if you already installed it before proceeding]
1. Install Samsung Magician 4.4 from this link (the link is from Samsung) and reboot. IGNORE any upgrade notification you get until you have completed the next step!
2. Enable RAPID Mode on the drive you want and reboot. Make sure that RAPID mode is working with a speed test, you will know when its working
3. Now perform an inplace upgrade to the software. For me, it only updated the software to 4.5 however I have the EVO 1tb drive installed so I wanted to get the lastest, 4.6. So I did a series of 2 upgrades.
I now have 4.6 running with RAPID Mode enabled. The kicker is, IF I should require backing out of RAPID mode, I will be unable to reenable with the current version of 4.6. I would have to downgrade and start these steps all over again. However in the entire year of owning the laptop, the only time I needed to reenable RAPID mode is when I was doing a clean install of my OS.
Hopefully Samsung will release an update soon.
Cheers
Dave