I got some improve on my hash rate speed. Before it usually used to work at 177Mh/s and now 188Mh/s.
I did the same config for the 3 rigs I have and the total gain was 30Mh/s it is like I have gotten another GPU  

However I'm gonna monitor my graph on the pool and see if I really had some gain... Let's see!!




- 17 Cards are Asus Radeon RX 580 OC 4GB - samsung memory
- 1 Card is Asus Radeon RX 580 OC 4GB - elpida memory



For me -strap and -rxboost were waste of time. They really increased the hash rate, but I was getting too much:
"GPU #0 got incorrect share. If you see this warning often, make sure you did not overclock it too much!"
So the hash rate reported by the pool decreased a little.

I was using:
-strap 2
-rxboost 21

And undervolting and overclocking with OverDriveNTool
-cvddc 870
-mvddc 850
-cclock 1170
-mclock 2010