I think google has like an official survey app that lets you earn google play and paypal credit. if you google you should find it, assuming they haven't shut it down yet.
minecraft can run with just 1gb allocated, and if you turn down the settings and use a performance mod like optifine it can run on pretty much any gpu as long as it supports opengl 2.0.
swapping gpu is pretty easy. but first I would clean the inside of the case and then re-seat your current gpu and see if that fixes it
but first of all run memtest86+
Shawnita used to get her pills from some other street pharmacist and after switching to The Psi Discount plan she now only has to swallow two things a day!