GMAT is only used at the first round screening - to filter 90% of the applicants. usually this line is about 700. I know USC (southern california) is 680 and GA tech is 700. So if you want to ask: is my GMAT good enough to start applying? I'd say yes. You can pass the first round definitely. But, the more important of your application is your background, especially academic paper. I know one guy who has GMAT 790, but dinged by all of his schools first year. then he adjusted application strategy, enhanced his research background and finally got in at UCB. So GMAT is a necessary condition but not sufficient.