I never, ever load XMP profiles, I prefer the old fashioned way by manually setting primary/secondary timings.
Hopefully the UD3H gets the fix soon, it was a nightmare trying to get c7 Flares to boot at 2600c8 with tight subs, I had to use the 2400 divider and then raise bclk to get there because the 2600 divider was a no go. Plus profiles are beyond broken, at least once you save them they are.
Although Albrecht is correct you should be able to boot at 2600 on auto, just saying.
. . .but I agree that tighter timings are better than looser and the UP5 is pretty efficient with auto settings and seems to work a bit better than it's predecessors, so can I haz UD3H bios:D