Maximum PC

Hey! After searching for a long time I think I will buy this ASUS ROG Laptop http://www.ebay.com/itm/ASUS-G75VW-BBK5 ... 19d7430f11 I want at least a GTX 660M which this has but I am curious can this laptop be upgraded to a GTX 675M or GTX 680M? I heard the GTX 680M uses laptop PCI-E 3.0 and if this is true could I use it on a 2.0 slot and would the difference from not using a 3.0 slot be noticeable? I want the freedom of being able to upgrade it in the future. My current laptop is a DELL Inspirion M5010 with a AMD Phenom II X3 and ATI Radeon 4250 HD. The CPU is decent but the GPU is junk. Really wish it was upgradable so I would like that freedom with my new ASUS. If not then that totally sucks but I will still buy it because a ATI 4250 384MB DDR3 VS. a Nvidia GTX 660M 2048MB GDDR5 would be quite the upgrade.

According to this, you can't really upgrade the GPU on the laptop you're looking at to anything more powerful. Also the GTX 680M upgrade on eBay costs about half as much as the laptop itself at the minimum (http://www.ebay.com/sch/i.html?_odkw=GTX+680M&_osacat=0&_from=R40&_trksid=p2045573.m570.l1313&_nkw=GeForce+GTX+680M&_sacat=0)