GTX 690 Low Gpu Usage

Hey guys, ever since I bought my gtx 690, there has been one thing about it that I have wondered if its normal or not. I'm assuming that this probably pertains to SLI configurations also, because that is essentially what the 690 is. Anyway, I was running mi afterburner to check my fps, temps, and what not, and I realized while looking in game that on most of the games I play, both of my gpu's never actually run at 100% utilization. For example, I was playing left for dead 2 maxed out (I play at 1920x1080 for the time being), and I was obviously getting a high enough framerate to get the job done (this isn't really an ideal game to test this on, i know), but I noticed that the usage of each gpu was only at 50%. I wondered i this would still happen if I disabled one of the GPUs, so I did. After doing that, I still had the same framerate, but the one gpu that was being used was near full utilization as it should be. So basically, i'm wondering why SLI is proving to not be very beneficial on most games for me, and why the 690 wants to utilize the same amount of graphics processing power either way. There's not really going to be a performance difference if the utilization is 1x100% or 2x50%. Of course it's not really that big of a deal on THIS game, but what concerns me is that the low utilization happens in other games also, and some more graphically intense games could definately benefit from both of the cards working at their full potential. It just seems weird that they wouldn't want to work at full force on some of my games, because sometimes in those games, less than half of each gpu being used is definately not enough to keep me above 60 fps all the time, sometimes it will drop below that, which sounds really sad and dissapointing to me for how powerful this card is supposed to be, and it's become very frustrating in some games, especially Planetside 2 and Borderlands 2 to name a couple. And it actually seems like the more graphically intense a situation on either one of those games get, the LESS of each gpu will be used, and i'm pretty sure it should be the other way around. Could there be something wrong with my 690 and the way it tries to utilize itself? I've heard so much talk about how powerful it is and how good of framerates people are getting but for me it's basically acting no better than a single 680 probably would Can someone please help? I'm lost...

Sorry for the huge wall of text, i'm just trying to be descriptive about my problem, and by the way, my processor is a stock i5 3570k, so I don't think bottlenecking should be a problem.