My screen new video card does not take up 100% of the screen

If you have 2 monitors attached to one video cards and one has a black border and the other does not, here is what to do to remove the border. First go to your video card control. In my case I am using a GeForce nVidia. I left click on the desk top and click on nVidia control panel.

Yours may be different. Click on the first monitor to view its resolution. Then click on the second monitor and make its resolution the same as the first. The bottom line both monitors must have the same.

Do not go above what your video card supports even if your monitor has a higher resolution. For example if your video card highest resolution is 1680 x 1050, set both monitors to that resolution (1680 x 1050.

I ran into the same issue when first setting up my own Acer H244HQ display over HDMI on my AMD Radeon HD 6970 cards.

The image over an HDMI connection can look as good as a DVI connection, with the right settings. I don't think AMD's CCC defaults to the optimum for monitors over HDMI though.

Keep the underscan/overscan settings as you had before, so the image fills 100% of the display.

Then, try looking at the Pixel Format settings associated with your HDMI display (I forget the actual location in the program where it is but it should be there). You should see a few options for formats: YCbCr, Partial RGB, and Full RGB. YCbCr is probably currently selected as the default. This is a color format typically used for movies, which is fine on a TV, but not good for a computer monitor. Change the setting to Full RGB and click Apply. The image should look much less "washed out" and a lot nicer.

EDIT

Another thing to try, if this doesn't fix the problem, is to adjust your Cleartype settings. Click the Start orb and type "Cleartype" and hit enter, and then follow the instructions in the wizard. This should help make your text much clearer to read.