Quad SLI

come down to what your looking for in your games. and how you want set up a gaming rig. most times sli or crossfire of the top cards are fine for most top gaming rigs now. most video card vendors do make cards with two gpu on them for people with money to flush. i would not want to toss most of my build money on gpus then by slow cpu and cheap motherboard.
if i was building a rig i use a good case like nxtz and a seal water cooler. a 256g or larger ssd and a main hard drive.
8/16g of real good fast ram and a good power supply like seasonic or cosair. if i was going for an all black look i drop in a sabertooth mb. there also a lot of good mb out there from other vendors. drop in two 670 or amd 7000 cards. use a i7 3570 as the main gaming rig cpu. uses a blueray drive for watching movies and use a tv as the monitor for games. may want to use a reg monitor for day to days stuff.