well I just installed a rx 580 inside the same case as my 1070. The 1070 is a blower style fan that keeps cool at its overclocked speed
the rx580 dual fan by asus gets HOT its running at 76 C while my MSI aero 1070 runs at 65 C
the rx runs to hot, I can see why BOTH amd and nvidia are now putting in blower fans while the cheap after market gtx are using a cooling system that makes the entire PC hot
its this hot and its in middle of winter, I am seriously considering selling both 1070 and rx 580 and just getting 2 water cooled 1080tis and be done with it,
no more fans, no more fans breaking, no more worrying about the heat in the summer.
at this rate in the summer the rx 580 will die it just runs to hot
IMHO, the open-style fans are fine as long as you have an open frame mining rig and run an external fan perpendicular to it. The 10-14 inch fan adds an additional ~50W to energy cost but they work well to force hot air out thru the spacing between graphics cards where hot air gets trapped.
Ive noticed that even tho open-style fans have heatsinks that are designed to force hot air out thru either the back or front end of graphics cards, when you have 5-19 cards stacked in parallel the temperature kinda get a little bit higher going from the first to the last in the fan direction.