If you own a high-end AMD card with the latest drivers, and are experiencing with some games - especially older ones - please try disabling AMD Virtual Super Resolution:
1) Open AMD Catalyst Control Center,
2) Go to Preferences to switch to Advanced Mode, if it's not already enabled,
3) Open the 'My Digital Flat Panels' page,
4) If 'Enable virtual super resolution' is enabled, please disable it.
5) Click Apply to save settings.