cannot enable HDR with eyefinity

Hello.
I want to enable hdr with AMD Eyefinity activated

I tried all I can do but there is no hdr option when Eyefinity is activated
of course hdr works correctly when Eyefinity is not activated for three of each monitors

I tried 5760 x 1080 / 11520 x 2160 settings to enable hdr.

* dxdiag says advanced color is not supported "ONLY WHEN" Eyefinity is activated

kindly help me. thanks