If you're using HWMonitor Pro then under the Tools or Options they have that box to log to a file.
In the standard version you can only save the monitoring data through the File Tab.
For changing the Video quality.
Open the CCC ( Catalyst Control Center)
In the left panel go down to Video Settings
Now scroll down the Right Panel, you'll see one entry with Optimizing Internet Video. Make sure it's off.
Disconnect all fans in the case and see if the "Knocking" is still on, I'm saying this because this is the first case of Knocking I have ever seen, Fans usually run pretty fast 600 to 1200 or 1800 RPM, they usually can't knock at those speeds, you can hear them screeching , brushing, crackling, breaking but not knocking.
You may have a wire with a socket dangling in the case that hits a fan blade every now and then and recoils into some part of the rig that could be "Knocking" or then the HDD knocks..:) and that's not very good.