If your going to get a 670 from EVGA, at least make sure its the FTW version. Get a 4GB FTW if you need it. I recommend the FTW version because its a 680 cooler on a 680 PCB, so you essentially have 680 cooling on a 670. Sure it can get a little loud, but its much quieter than a standard reference cooler. Its dead silent at idle.
Actually Sumukh the 670 from Gigabyte won't give room for overclocking. Because its voltage locked .