Software that doesn't take full advantage of the hardware is the main issue nowdays. Even when using a basic dual GPU setup for example you only get 40-70% more fps on average, that even on an i7 920 setup.
Sooooo yeah ... you could have a quad GPU setup but trust me ... you most likely won't , especially when adding a third GPU to the mix only results in a 10- 20% fps increase.
Nevertheless you will see an increase in the min fps which is in my opinion the important factor.http://www.evga.com/products/moreinfo.asp?pn=170-BL-E762-A1
here you'll find a proper motherboard that can accommodate ... well ... let's just say that this one will do ... for now