When the system is under load, especially when the GPU and CPU max out, like say, when you are gaming, the BIOS/Chipset has a safety feature that will throttle down the system to prevent damage. Unfortunately I feel that the protection is triggered too easily, and many people will have a performance loss while playing their favorite games.
This will require a BIOS fix, but until then, there is a great workaround provided by Unclewebb. It's called ThrottleStop, and version 3 was updated to support Sandybridge systems. The culprit is the Bidirectional PROCHOT function, which handles this throttle feature. What you want to do is disable it, and it only needs to be configured once every boot-up, until a BIOS update exists. Also config it to Start Minimized if you are going to have it start at Windows boot.
Go ahead and download the current build, and install it. When you got it running, click on options. You want to enable the BD PROCHOT control here.
Then you can untick BD PROCHOT on the main screen and then Save it. This way whenever you start up TS, it will autodisable the setting. Then just throw a shortcut of TS into your StartUp folder, and you'll be good to go. Once it's set, yo can minimize it, or close the application. The setting will stick until your next reboot.