DVI vs HDMI - image is too large

Here is my setup: I have the following video card and monitor:
http://www.newegg.com/Product/Prod [...] 6814127339
http://www.newegg.com/Product/Prod [...] 6824116401

I am running Windows 7 and have the latest ATI driver for the video card, and the resolution is set to 1920X1080.

Here is the problem: when I connect the monitor using a DVI cable, everything is fine. But if I replace the DVI cable with an HDMI cable and the DVI/HDMI adapter that came with the video card, the image is larger than the screen. In other words, the edges of the image (top, bottom, left, and right) are all off screen a little bit, so for example I can't see the taskbar at the bottom of the screen, nor can I see the top edge of my browser where it says "Tom's Hardware Forums", etc.

Here is why I can't fix it: I can't adjust the image size on the monitor because the option is greyed out on the on screen display. Neither is there any way to resize it using the Catalyst Control Center or Windows' display options.

Here is why I'm about to smash my monitor: Why is this happening? I realize I could just go back to the DVI cable, but I just don't see any reason that this HDMI setup shouldn't work exactly the same.

Right, I already understand that, as I pointed out in my post. But my question is "Why is this happening?"

I opened up the DPI control panel and it shows a little ruler on the screen, so I got out my real ruler and held it up for comparison. The ruler on the screen is larger than my real ruler, so it looks like maybe this is where the problem is arising. Here's the rub: I can't lower the DPI setting. I can raise it with no problem, but if I try to type in something lower than 100% it immediately resets itself to 100%.

Perhaps just try forcing it through the display properties panel in the cat's and see if that make a difference, also what scaling options are you using?

In the desktop properties, I said display by accident, you can try forcing a setting, not sure if that will help at all.

THe scaling options I cannot find in the cat's, I was sure they were there a minute ago.

You may also have some scaling options in your monitor OSD.

I don't think it would solve anything really bit just checking as you said 16 x 10 fitted perfectly.

Ok, but where do I change that setting?

Excellent, this is what I needed to know! Why have they made it so hard to find this stuff in the CCC?

Anyway, now the picture fits, but it's sort of fuzzy, especially text. Is there some other setting I need to adjust to make it sharp again?

Also, since DVI and HDMI are supposedly identical with regards to video, why do I need to adjust the scaling for the HDMI connection whereas it was already correct when I was using the DVI connection?