is not apples fault...that HD 515 is Intels fault
Have you seen the specs of the intel core m chips? Probably shouldn't trust Apple's word so much.
I'm not sure why but intel says they support 2160p at 60hz and apple says they don't. Could be a typo.
Broadwell core m 1600 at 60hz.
Skylake core m 2160 at 60hz.