I have reported this issue to Asus support but I don't think I am being understood.
X99 set-up and working with a 5820K processor and Corsair 16GB (4x4) of DDR 4 memory.
The Corsair memory has two XMP profiles. One for 2666 which is supported. And one for 2800 which is not.
In AI Suite 3 when running the 5-way optimisation routing, it chooses the 2800 profile but implements it totally wrongly. The 2800 profile actually should be pushing a 125MHz strap. But what happens with AI Suite, is it leaves the strap at 100, wrongly sets the speed to DDR 2400 but correctly sets the timings of 2800 and the voltage of 2800 (1.35V). It is completely messed up. If I force the timing to 2800 in the BIOS it is unstable, because 2800 with this memory requires the 125 strap for stability. In fact AI Suite should choose the lowest XMP profile, not the highest by default (or at least give a choice)
Additonally AI Suite 3 reports the DRAM frequency as 3.1GHz no matter what it actually is. Of course MemTweakIt shows it correctly.
Incidentally currently running the 5820K at 4GHz which is so completely easy. 4.2GHz using CPU level up works to a point as it runs for normal operation, but I get a BSOD after a short time in Prime95 28.x. CPU temps are nowhere near limits although its hard to be sure as AI Suite reports the CPU temperature about 10 degrees lower than the latest version of CPUID Hardware monitor.