It kinda sounds like you might have a dead/defective GPU. I would definitely try to RMA (call the shop you bought it from (Newegg/Amazon, they'll email you a Return Shipping label which you then save on an USB drive, go to an UPS or Fedex office; print the label there and present the box to them. The return label pays for the shipping). But yeah if your monitor is turning different colors that's definitely a defective GPU.

This is my advice, someone else might have other troubleshooting options though.