R9 270 problem(s)

I got my R9 270 about 3 months ago and have been having trouble with it since the first day. So the thing is I have been getting strange glitches in some games. When I play LoL some objects would sometimes just spread all over the screen and some small parts of the map texture become randomly rainbow coloured. For some reason alt-tabbing fixes both issues. I have also been playing battlefield hardline lately, and it happened 4-6 times in 10 hours of gameplay that I got some objecets flickering all over the screen (alt-tabbing didnt fix it this time). It also happens occasionaly in bf that a small area of the screen (close to bottom right corner) would start flickering black. Other games and 3d apps seem to perform fine in terms of textures but there is another issue. The level of detail changing trasitions are absulutely horrible in all battlefield and arma games. When moving forward the objects just randomly appear (grass, bushes) and the shadow detail level changes without a smooth transition. When speaking of shadows, they are jaggy and sometimes flickering. I dodnt bother about the issues to much since I mostly play LoL, but I reinstalled my drivers yesterday and now another issue appeared which has a direct influence on my LoL gameplay - when I alt-tab windows starts lagging horribly. Not to mention the (sometimes) unbearable coil-whine coming form the gpu when running the game above 150 FPS.

I am wondering whether I should send the gpu back, since I am not sure if the issues are caused by the gpu or the combination of my other components (everything was working fine on my 650 ti).

R9 270 problem(s)