Could you not just set the CPU/DRAM ratio to 100:100 to see the option to set your RAM to 2000?Then set your timings manually...

Are you in fixed voltage mode or offset?

4.7 seems to be your sweetspot what with the extra vcore that 4.8 needs and the instability it showsAlso I wouldn't bother using IBT for stability testing an Ivy CPU, just use Prime blend for a few hours and then use your PC for what you normally use...