the difference between i5 and i7:
Won't go into too much detail but hyperthreading is pretty much two virtual processing cores on one physical core.
For your problem:
You said two graphics cards were installed, but really theres only one. The other "graphics card" is actually built on to your motherboard, and so really doesn't count as a "graphics card".
I'm thinking maybe you haven't updated your drivers
properly, so: Drivers | GeForce
but I think I found the driver
for you, which is: Drivers | GeForce
and download your latest driver. Follow all the instruction and HOPEFULLY it'll work.
Also, check your Graphics Card has the specs required to play the game (if it can only run the game at minimum specs, expect to have low fps).
You can try seeing if your computer is using your onboard or your video card. Start > Search > "Device Manager" (without quotations) > click Device Manager.
Expand the arrow leading into "Display Adaptors" and it should tell you which one you're currently using.
Since I don't use laptops (Only my desktop, phone and/or tablet) I can't actually see what the problem is, but if those other suggestions fail then the only reason I can think of is your card was screwed up during the manufacturing process (or somewhere along the line) - if it is, just call Lenovo (they should have the customer support phone number on the receipt) and ask the technicians about your problem.