Comment 69 for bug 1431753

This fix works for me although I could not properly test any 3D applications. My Steam client is acting weird and does not see my installed games anymore, complaining about partition being non-executable. Also it was hanging at after entering password. I had to create a new user and start fresh.

Hardware: GTX 770M with 3GB on Asus G751-JX laptop.

Here are simple steps to test without getting too much into "proposed": (for 14.04)
1) Run "Software & Updates" application,
2) Click on "Updates" tab,
3) Tick on "Pre-release updates (trusty-proposed)" and hit Close button.
4) Authorize the change and close. It will ask for refreshing software information. Hit Reload and allow this.
5) Run the same app again on item 1 above and go to "Additional Drivers" tab. Now you should see 346 and 340 builds. Chose what you need and hit "Apply Changes"
6) After you are done, reboot first to test. You can repeat steps 1-3 again and disable proposed in order to avoid installing proposed packages for other applications.