Shmee, I really liked my 2 R9290s in CF, especially since they were both water cooled with EK blocks and I used that MO-RA3-420 Pro radiator which I still have. Sold them to offset the cost of the new GTX 1080. When I built the third rig, 6700k I was lucky enough to snag, AT RETAIL, one of the Sapphire RX 480 8G. Having had experience with the R9 290, the biggest difference right away was the big drop in power draw for the performance. I was tempted to water cool it also but with the block being nearly 1/2 the price of the card it was hard to justify, even with the reference cooler.
I thought I was done with CF, but a number of factors played into my decision to change course.
First I found an EXACT reference Sapphire for the same price I paid for my first.
Second, CF profiles for these cards seem to be updated constantly.
Third, Vega seems to be pushed back further and further. Perhaps the upcoming ZEN release has AMD so focused on it that Vega was pushed back. Who knows. Fourth, I already have 2 other machines with relatively new and high end Nvidia cards (GTX1080/560x and GTX980TI SC/4790k) so I decided AMD needed to have a look see, especially with the release of Polaris. Please don't read into this that I am critical of the GTX1080/GTX1070 or even the GTX1060. I am NOT. They are excellent cards and compelling choices for a single computer owner (I note you still have the dual 290s in another system but your main one in your sig shows the GTX1070 SMART MOVE.).
My next reason was I now own a LG29UM67P monitor for the 3rd rig. It has Freesync support so the AMD choice was made.
Finally, I have to admit, as they say," curiousity killed the cat". In this case the kitten is still purring as are the dual 480s. Overall power draw, as measured by my KILL A WATT meter on the 6700k/Daul 480 rig below, running AIDA64 stress test, stressing ALL components was 480W max with the meter constantly hovering at 465W. I remember doing that with the dual 290s in the 4790k rig and being in the 675 to 750W range.
I am fascinated by multi-gpu technology and was interested to see how close the dual 480s came to the GTX1080.
Dual Vegas? HUBBA HUBBA!