I neglected one solution to having a 4k Display with OpenBSD. I was reading about Haswell and 4k in context of the Mac mini which uses a low power series of processors that do not support 4k at 60 Hz. The regular Haswell chips like the Xeon E3 1275 v3 I am using now, do support 4k at 60 Hz using DisplayPort. My Dell P4317Q seems to be working fine at 4k with inteldrm(4) and this processor. Thanks for the suggestions.
I will also test my Skylake build with efifb(4) and wsfb(4) once my Xeon E3 1275 v5 arrives in a few days but I suspect it will be very slow as has been predicted. Bryan
