Back up for a MIN....
First off... How do you know your clocks speeds while in game? What did you use to gather this information?
Second it is not accurate that nothing can revmove AMD Drives as De.Das. Dude says. I do it all the time and have no issues. As a matter of fact I have had just as many problems with Nvidia's Drivers and this type of issue as AMD's.
Lets do some troubleshooting.
Download GPU-Z and run the Stress test from it. Observe your clock speeds under the monitoring tab to verify your problem is really happening.
If it is.... verify you have no other programs or unessential processes running in the background. (Something that could be interfering with your clocks speeds) I had a Asus Motherboard Sound driver once that overclocked my card by 10mhz for no reason once.
If this doesn't work.... uninstall all Overclocking Programs and then reboot. After that re-run the first test and see if the issue still occurs.
If you do end up uninstalling the Drivers Follow these steps..
1. Turn off Windows Update
2. Uninstall AMD Drivers
3. Reboot into Safe mode
4. Use your preference of a Driver Cleaner software
5. Reboot into Regular Windows Start up.
6. Install New Drivers.
7. Reboot Windows
8. Turn Back on Windows update
9. Test to see if problem still occurs
If this doesn't work I can direct you a more in-depth Driver cleaning procedure.
Try these things out and report back to us.
dude the latest 7790 beta drivers are really bad. they completely fuck the os up. i had to do a reinstall of the os to clean the issue.
the problem was drivers would be removed and installed, but CCC would fail to start, and after the fuck up no mater how many ways you try it will say that there was some problem in the installation.
so, its not just me.
this bonaire based chip has been especially plagued with crappy drivers. beta AND whql. pre october, all the drivers released caused freezes or bad frame rates for me as well, so i was forced to use the provided drivers. finally after repeated exchanges with amd explaining everything they seemed to have got it right.
FYI 7790 and 260 or the 260X are same chips.
dont go ahead and just say something some is saying is untrue just because you havent seen it yourself.
if you go through my activity you will even probably find the thread where i was looking for a solution to this.
what i think has happend with op is he has somehow managed to install one of the bad apples and is now stuck. after all, i have already suggested what you said and he has tried to no avail.
next time if you balantly disrespect someone, its really rude.
here are some examples of this problem
https://www.google.co.in/search?q=7790 driver issues&oq=7790 driver issues&aqs=chrome..69i57.4026j0j1&sourceid=chrome&espv=210&es_sm=93&ie=UTF-8
see how many hits its has?