from what i see on the valley scores chart, guskline doesn´t seem to do much high overclocking, even though he has a custom water loop on his 670sli
https://docs.google.com/spreadsheet...bjQ2UWZQUDZ0dVE&single=true&gid=0&output=html
at oc out of the box with no voltage tweak, i think good custom r9 290 might be stronger
then there is the question of monitor resolution
if you use your full hd non 120Hz monitor i strongly recommend trying downsampling if you never tried it before (especially using such powerful cards/multi gpu setups)
it can be done very easily on nvidia cards (i hear it´s more of an issue on amd cards)
try it out with your gtx 670sli rig, it´s amazing for picture quality
downsampling on 1440p is probably more something for dual titans (6Gb)
but 1440p looks way better anyway, ds not so much recommended as with 1080p
then there is another question: if you ask for both team red and green you obviously don´t prefer either by much
if i had had 4 nvidias as my last cards (and i only know your current rigs) and i´d keep a 670sli setup for doing downsampling on my smaller monitor,
i think i´d go amd for the big monitor (also good suit for having double the vram over 670s), just for trying the other brand for a change (unless i needed an exclusive feature, or it were public consent that either of the choices were crappy, but it sounds like performance is pretty much eye to eye)
it´s exactly what i´m doing
2560x1080 monitor: sli 770s doing downsampling
6000x1080 triple monitor setup: upcoming r9 290 (i really hope it works without display port monitors or accepts my dp-->dvi active adapter)
just that i didn´t change from a load of nvidias, had more amd cards in the past
but that´s when i went 770sli for a change
then again, if the amds are blown up in price due to the mining, maybe 780 is the way to go,
at the same price, for competitive with each other cards, i´d always go nvidia, they somehow have that extra premium sparkle about them (but that´s purely a matter of taste)
it´s like a corvette or a porsche, the corvette will perform as admirably, but if given the choice, price aside, i´d always want the porsche (then again, i´m german, lol)