到這裡看，再選左邊對應的產品，找到737-37877

http://support.ati.com/ics/support/....asp?deptID=894

轉貼一下整篇好了，似乎跟開啟OverDriver有關，但是沒開OverDriver好像還是有問題。

Knowledge Base
AMD Customer Care Site Map > Radeon Support - PC > Radeon HD 4870 > Knowledge Base > ATI Software >
737-37877: Visual corruption and possible graphics stability issues when over-clocking the graphics engine or graphics memory in dual-display mode

The information in this article applies to the following configuration(s):

* Catalyst Control Software Suite
* Radeon™ HD4800 series
* Radeon™ HD4600 series
* Radeon™ HD4500 series
* Radeon™ HD4300 series
* Windows Vista 32-bit Edition
* Windows Vista 64-bit Edition
* Windows XP Professional
* Windows XP Home Edition
* Windows XP Media Center Edition
* Windows XP Professional x64 Edition

Symptoms:

Unlocking ATI Overdrive™ and over-clocking graphics engine or graphics memory in dual-display configurations (clone mode and extended desktop) can result in visual corruption or graphics stability issues.

Solution:

Switch back to a single display configuration when over-clocking the ATI Radeon™ HD 4800 Series. A future Catalyst release is planned to resolve this issue.