CaptainJang :
Im on 8gb ram and probably adding another 8gb. i7 4790 is my cpu. What GPU would you recommend sir for my case? Thanks in advance. Still getting opinions.

somewhat im reconsidering gtx970 because as you've said single card is more than sufficient.
Well, if you aren't doing any gaming with this rig I wouldn't spend more than $250 on a GPU. For optimized rendering and simulation, that is where the Fire Pro/Quadro cards really shine. For OpenGL computations, AMD has the advantage as the GCN architecture allows for more raw computations when compared to Nvidia. Something like the R9 290 can be had for about $250.
http://www.newegg.com/Product/Product.aspx?Item=N82E16814131569&cm_re=r9_290-_-14-131-569-_-Product
GTX 960 can be had for $230:
http://www.newegg.com/Product/Product.aspx?Item=N82E16814487128&cm_re=gtx_960-_-14-487-091-_-Product
If you also want to use the card for gaming, check out the R9 290X for $310:
http://www.newegg.com/Product/Product.aspx?Item=N82E16814131665&cm_re=r9_290x-_-14-131-665-_-Product
I'd recommend a 290X over a 970 as an overclocked 290X actually performs better for less when compared to the 970. The R9 390 is just a rebadged 290X.
GTX 980 and Fury could potentially be options, but if you are going to budget $500 for a GPU you may as well save up for the big kahuna, the 980 Ti.