I just want to know which one is better, and by how much.
GT 640
http://www.amazon.com/Galaxy-GeForce-Express-Graphics-64TGF8HX6FTZ/dp/B0084ZYHMU/ref=sr_1_5?ie=UTF8&qid=1393550762&sr=8-5&keywords=Nvidia+geforce+gt+640
Gtx 750(Not ti)
http://www.amazon.com/MSI-N750-TF-1GD5-OC/dp/B00I6DLIFO/ref=sr_1_3?ie=UTF8&qid=1393550794&sr=8-3&keywords=msi+gtx750