Hello everyone, I'm having a weird issue where my late 2012 iMac exhibits weird glitches (image below). It doesn't happen very often but when its starts to happen, it really goes crazy for a while. I also noticed things like quick preview and premiere pro like induce this issue. It seems to me like every time the gpu is require to do a hard tasks it craps out. Has anyone experienced this? would you say its a bad gpu?