I have a R9 390 8GB video card. It was very cheap, because it was not tested before. When I powered on the PC with the graphics card, the screen have straight lines. When I took it apart, I saw that one memory chip is missing. I contacted with a BGA reballer, and He said that is unrepairable, because the PCB is damaged when someone removed the chip. My question is that I can force somehow the graphics card to operate with less memory and work fine?