Colour difference between DVI and HDMI

[Darxide]

I just replaced my 4 year old Iiyama 26" with 2 identical LG 24" LED monitors.
ATM I'm using a cheap Radeon 7750 card while I wait on the new R9 cards to arrive, so I can't run both of DVI as I would have liked to.
This card has 1 DVI, 1 HDMI and 1 VGA. So obviously I'm using DVI and HDMI for the 2 monitors. Now, the monitor on the HDMI connection displayed the picture with overscan borders, so I used the Radeon driver to enable overscan compensation to remove it. But, the result is that the colour on that monitor is now different to the DVI one.
It looks like you would expect it to if the picture were scaled and not using the monitors native. Hard to explain, it just looks a little 'off', and not quite as sharp as the one using DVI.
Is there anything I can do to fix that? Or is that normal for HDMI?
I'll be changing cards soon anyway, and hopefully the new R9 will have 2 DVI ports which will hopefully solve the issue. I say hopefully because I've noticed a lot of the current 78xx and 79xx only have 1 DVI.

Quick edit. Catalyst control centre seems to identify them differently. It shows both screens as the same model number, but lists one as a 'digital flat panel' and the other as 'digital TV'.

[CrazyNutz]

The best way to handle this is to disable overscan in the monitor's setup menu (i.e. get into the menu of the monitor itself).

Now the ugly part is some monitors do not have overscan settings.

[Darxide]

The best way to handle this is to disable overscan in the monitor's setup menu (i.e. get into the menu of the monitor itself).

Now the ugly part is some monitors do not have overscan settings.

Thanks for the suggestion. I looked in the monitors menu and overscan is already disabled.
I'm convinced it's because of the way the driver is detecting them, but I can't find a way to change it.
It has one listed as DFP @ 1920x1080, and the other as DTV @1080p.

I guess I'll just have to put up with it until I get a new card with 2 DVI's.