No they don't know what they're ttalking about. You don't NEED an I7 an I5 2500K is really perfect for gaming. Here is how it would look if you broke it down
So really the I5 is the same as the I7 but without the hyperthreading, and a 2mb smaller cache. The fact is games right now don't use hyperthreading and 2mb of cache isn't really going to make a difference either. So you save 100 dollars on two features that games don't use and you can put that money to something else like a better video card or SSD.
Yes it will work if it has two PCI-E slots either in a 8x/8x, 16x/8x or 16x/16x slot configuration. The main thing is that you need to make sure you have good ventilation in the case because two cards will create a good bit of heat.
ok so its set, my first build will be a asus maximus extreme z z68,i5 2500k,h100 with 2 more cougar 120mm for a push pull config,8 gigs of corsair vengance low proofile 1600mhz ram,xfx r7970 black edition,1tb samsung 7200rpm hdd ,a blueray cdrom dvdrom,1000w coolermaster modular psu and a hafX then later i have room for 32 gigs of ram even tho im only going to upgrade to 16 and i will add another r7970 and eventually a 120gb ssd