It should usually try to connect with the highest one.
I have the previous model of the laptop you're looking at, a Sager 8690, almost the same specs except yours has a few newer components, same video card though. It's a very good solid laptop, and it is right between desktop replacement and portable laptop (don't kid yourself about netbook style portability).
The system runs very well, I initially had problems with the video card, but it turns out it was just NVidia being stupid with their mobile drivers, a recent driver update fixed those issues.
The system gets only about 45 minutes of power on average, although usually going as low as only 30 minutes if you're doing stuff like browsing heavily and watching web videos. You can maybe stretch it to 1 hour by turning all the options down, but even that's pushing it and you're not going to enjoy that experience. This is definitely a system that you want to have plugged in, nor is it really mobile. Its weight means you want to carry it in a backback, and when handling use both hands. By backpack, I really mean a backpack, not a single strap laptop tote or similar. It's lighter than those monstrous desktop replacement 17"+ laptops, but you'll still feel it.
This may have changed with the latest version, but the fans will be louder than you're used to at the start, but not overly loud. It will ramp up rapidly if you're playing anything that will use full CPU and GPU.
15.6" screen is good as well, however you'll have to get used to a full 1920x1080 (basically 1080p) being displayed at that 15.6" size. Text will be smaller, so make sure your eyes can handle it. But otherwise the screen is beautiful.
The Sagers also have ports a plenty, and it looks like that model actually has a few more too.
As for how it runs games, it runs them great. Pretty much ties even, often better than my desktop.
Now for a major downside: the touchpad. The 8690 has a sentilec (or similarly named) touchpad which close to being worthless for anything but the most basic moving the cursor around. Synaptics currently holds a lot of patents on the best touchpad features, so this pad doesn't even have the feature where you can scroll pages using the right edge of the pad. It's sensitivity is finicky, often registering taps when you aren't trying to, and often not registering taps when you do. Any special features like multi-touch is there as more of a bullet point afterthought rather than being fleshed out, at best they don't work, and when they do you can't configure them to be how you want. Not to mention driver support is abysmal for this touchpad.
So get a mouse, I recommend this again even though as I gamer I know you already planned to get one, but I really am not kidding about how bad I think this touchpad is.
The Asus gaming laptops are also good, but the problem I have with those is that they're huge. Their 15.6" laptop is pretty much on par with an 17" laptop in size. Although I do like how they look.