If you're getting a Dell (or other laptops, but I know it's fairly common in Dell laptops) try to avoid anything with AMD SmartShift. This feature is designed only for Windows and will cause problems with Linux.
I've been told of a pretty simple fix, so it's not the end of the world, but if you can avoid it I would.
Great. I should add that the solution I mentioned was done on Mint, but it's a kernel parameter so I'd imagine it's not too distro-specific (I'm very new to Linux though so I may be wrong).
Here is the forum thread if you want to look for yourself. The actual solution should be the third-to-last reply.
The user added in the last comment that this problem may actually be fixed on a lot of SmartShift laptops, so it may not come up at all if you do get one.