I am not sure if its my GPU / Memory or Hard drive thats failing. For example if I'm running more than one instance of chrome and running an application that takes up a lot of resources, my system will start to lag and freeze. When I launch Photoshop the GPU feature disables automatically, this also lags when I click on menus and when working on documents in Photoshop. I really dont know where to start, if i should buy a new graphics card or test the memory or could it be my OS drive?
System: Windows 7 64bit, ATI Raedeon 5850, Corsair 2x4GB
Here is a screenshot of the TaskManager: