OpenGL error with windows 8.1

Hi all, my O.S. is windows 8.1 Pro.

About 2 months I have this operating system, previously I was using windows 7.
I have played for 2 years with windows 7 for a few steam games, such as team fortress 2, garr’ys mod, etc.
The problem is that windows 8.1 the games don’t run with OpenGL ( as happened with windows 7 ) but with directx9.
In this way, the games run very bad, lag, low fps, etc… Problems with opengl that never existed.
All my drivers are up to date, how can i play my favourite games with opengl and not with directx?

These are the most important technical specifications of my pc
CPU: Intel core I7 920
Ram: 6GB 1600 mhz 7-8-7-20
VGA: AMD 6990 4GB

Thanks, good job.