can a alienware m17x R4 notebook be upgraded from 660m to a 680m?? i wanna get this 680m off ebay but i wanna make sure its compatible w my mobo.. any help would be appreciated.
You have to be extremely careful when replacing laptop video cards. Your best course of action would have been to purchased the 680m when you purchased your laptop, Dell can add in pretty much anything even if it's not available on their website.
Laptop video cards use firmware that's custom tailored by each OEM, this is necessary to support the functions specific to each laptop's thermal design, feature set, and the various card configurations. Most mobile cards are significantly more anaemic when it comes to output configurations than desktop cards. This is why most laptops lack dual-link DVI-I connectors (even if a dual link port is included, only single link may be wired), too many wires. Then there's also the rumors of vendor lock-in.
So, you would have to make sure that you get a 680m that is designed to work with Dell laptops, which would basically mean getting one from Dell's Alienware service department.