Hi Ban camp,
1. Since from when are you facing this issue?
2. Does this issue occur while playing other games?
Method 1:
I suggest you to delete the power plan on your computer and check if the issue gets fixed.
Refer:
Change, create, or delete a power plan (scheme)
http://windows.microsoft.com/en-US/windows7/Change-create-or-delete-a-power-plan-scheme
Method 2:
You may vary the hardware acceleration by doing the following and check if that fixes the issue:
a. Open Screen Resolution by clicking the Start button, clicking Control Panel, and then, under Appearance and Personalization, clicking Adjust screen resolution.
b. Click Advanced Settings, click the Troubleshoot tab, and then click Change settings.
Note that some video card drivers do not permit you to change settings.
c. Move the Hardware acceleration slider to increase/ reduce the video hardware acceleration.
Method 3:
You may uninstall the display adapter and re-install the same from Device Manager.
a. Click Start, type Device Manager in the Start search box and hit Enter.
b. Locate Display adapter and expand the same.
c. Select the problem display adapter you wish to uninstall.
d. Right-click and select Uninstall.
Follow the on-screen instructions. Restart the computer, if required.
After the computer restarts, visit the manufacturer’s website and download and install the latest display drivers.
Refer:
Update a driver for hardware that isn't working properly
http://windows.microsoft.com/en-us/windows7/Update-a-driver-for-hardware-that-isnt-working-properly
Update drivers: recommended links
http://windows.microsoft.com/en-US/windows7/Update-drivers-recommended-links
Also try updating the chipset drivers on your computer.
Also refer:
Prove your computer's gaming performance:
http://support.microsoft.com/kb/815069
Gaming in Windows 7:
http://windows.microsoft.com/en-US/windows/discover/gaming
Ways to improve display quality:
http://windows.microsoft.com/en-US/windows7/Ways-to-improve-display-quality
Fixing game performance problems:
http://windows.microsoft.com/en-US/windows7/Fixing-game-performance-problems
Thanks and Regards:
I. Suuresh Kumar - Microsoft Support.
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