Fly demanding games

Good day, just start with the characteristics
amd fx 8300
powercolor radeon r9 380 8 GB
ram 8 GB
windows 8.1 / 10

So, started to hang the computer in demanding games such as : battlefield 1, Batman AK. CS GO normal flight. BUT! Noticed a shoal. Before there was 200-300 fps, and now 100-200, 300 have not seen for a long time.
What could be the problem? Overheating no, the comp year in summer, the temperature of the GPU reached 97, but with MSI Afterburnern until 86 where it is now 76-83 edge. Percent generally not heated degrees to 50 is high, in idle 18-23.
P. S. the problem started about a month and a half ago. First, similarly hung the mafia 3 (after 5-10 minutes of play), the problem was resolved by rolling back BIOS to previous version
P. P. S when you install the latest video card driver CS GO observed white stripes across the whole screen.