With an APU you want to uninstall all the AMD built in graphics drivers, but NOT the chipset drivers. Those are two different driver sets, so make sure you didn't wipe out all the AMD drivers.
CSGO is not a demanding game, but it does scale up in performance with a faster CPU. If you run the game at a resolution your card can handle, like 1080p, and note the framerate, then lower the resolution to 720p and benchmark the game again, and the framerate didn't change, then your APU is holding you back.
Another clue this is the problem is if running the game at high or low settings makes no difference. The reason that happens is that your videocard can't run it any faster at low settings because your APU is holding it back. Another way to verify this is to run MSI Afterburner as you test the game. Check to see what CPU and GPU usage percentage is like. If CPU usage is up near 100% but GPU usage is lower, like 80%, then this is evidence your APU is running the game the best it can.