So recently I switched up from using a VGA cable to an HDMI cable on my HTPC and was greeted with a black border around the screen. No problem, just adjust the video scaling and be done with it yes? Unfortunately no. There are tons of posts by people looking for the solution to this problem and not all answers are effective. ATI certainly must know of this deficiency and with the number of people hooking laptops, htpc and business computers up to lcd tvs these days you would think it would be a priority to fix it.

I won’t rehash what has already been explained. AJ does a great job of explaining how to get most people up and running here - http://www.aoclarkejr.com/ati-catalyst-9-9-overcan-and-underscan-options.html

However this article is for the people who this does not work for or who do not want to install the ATI Catalyst Control Center. I happen to be both types. For me selecting “Configure” on my monitor just brought me back to the ATI Welcome Screen. Awesome.

Before we begin ensure that your TV is configured correctly. On my Samsung LCD TV I had to change the picture type to “Just Fit.” This caused my HDMI underscan problem to become slightly less worse, but did not fix the issue.

To fix your display:

1. Write down the resolution and display frequency you are running at
2. Start -> Run -> regedit
3. HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Video
4. On my machine there were five subfolders in this key. Each of these subfolders contained keys named 0000 and 1111. Only one of these subfolders contained a ton of entries while the rest had only six entries. The subfolder with a ton of entries is the folder you want to be working with.
5. Backup the 0000 and 1111 keys. Don’t just backup the whole video folder or subfolder.
6. Select the 0000 folder and search for your tv’s resolution. In my case it was 1920×1080.
7. There will be multiple entries found in the format Name ResolutionxFrequency. eg:
   • DALR6 CRT1920x1080x0x59 - I believe this is your VGA connection
   • DALR6 DFPI 21920x1080x0x59 - this was hdmi for me
8. Edit the key that matches your resolution AND frequency – change everything to zeroes
9. There is a corresponding key in the 0001 folder. Change that one also.
10. Change your monitor resolution and then change it back to 1920×1080 or whatever you are using
11. The underscan should be gone

I tried to figure out what these keys control, but failed to decipher what the binary representations were. I even wrote a little program to try and convert the key to hex/string/int/decimal/etc with no success. If anyone could provide feedback on this it would be good karma. Logical sense would say it should be a decimal like .01 or an integer like 1 to represent 1%.

I’ve had this post waiting in the wings for weeks and of course just as I am about to post all this crap ATI releases Catalyst 10.6 which appears to have fixed the problem where the welcome screen doesn’t appear. Ugh.