You can run up too a GT 780 mxm with out any problems …I use a GT 760 mxm 3.0 B with 2gb’s of ram to keep the thermals lower. it needs to be installed on high sierra if possible and it’s a straight swap for the amd one that’s toast… Get one with the Dell Alienware bios or you’ll have to flash the bios before you install it. you don’t lose any features like people say … Lots of good guides on the internet and YouTube , and you will need to remove the motherboard. Max out the ram while your in there and add 1 or 2 SSD’s for storage as there is an extra sata header on the motherboard that is unused, but you’ll need an extra long cable I think it’s about 16 inches and a splitter for the power. I also used a duel 2.5 to 3.5 drive cage to replace the spinning hard drive and dropped in a i7 2600s CPU…Your biggest performance gains will be from the gpu, ram and SSD’s I ran mine in raid zero. once your up and running you can install Mohave without any hacks and still get a few good years out of your machine for a cheap investment… you will not lose the boot screen or screen dimming that’s bullshit …I’ve done this mod several times. If you don’t swap the CPU redo the thermal paste anyways. Lot’s of good tutorials on line that’s why I’m not going to give you a step by step…Good luck it’s not as difficult as it sounds.