Hello, I am just learning about computers and I want to upgrade the Nvidia GTX 745 in my computer to an Nvidia GTX 1060. I was ready to buy the graphics card when I realized that my PSU probably won't support the 1060. I have the standard 240W PSU and I read that the 1060 requires at least 400W. (I know that AlienWare does make a 330W PSU but it says 400W. I've alos heard from a few people that the 330W will run the 1060 but I just want to be sure.) All of my friends have computers with internal power supplies but for some reason the X51 R2 (and maybe others I'm not sure) has an external PSU like a laptop would. Is there an external PSU that is at lease 400W or do they not exist? Or is there a way I could add an internal PSU?