ATI 3870 unable to display 1680 x 1050 in Windows 7

[sculptor]

I have built a small pc (for playing video, listening to music, and web surfing) using some old components. I have used PowerColour PCS ATI 3870 for video and downloaded Cat 9.11. OS is Windows 7 Home Premium.
The monitor I am using is a Samsung SM205BW with a native res of 1680 x 1050.
My problem is the 1680 x 1050 res is missing from the available resolutions and Cat 9.11 dosent appear to have anyway to force this res.
I have used the card with Windows XP at 1680 x 1050 so I cant see that it is anything to do with the cards bios.
Does anyone know of a fix?
My monitor display goes black and displays a dialog box "not optimum resolution" which moves around the screen whenever I try 1440 x 900 or any other res, other than 1280 x 1024.

sculptor.

 

[Disjunto]

you should be able to create a custom res in CCC, let me go work out how

 

[MadMatty]

Should be a simple case of installing the driver from the monitor cd.

 

[sculptor]

MadMatty, yes I thought the same at first.
Tried it and not a bit of difference, even downloaded the driver from Samsung incase they had a newer version.
Thanks for your suggestion anyway mate.
Im using the d/sub conection but I cant see how that would effect the available resolutions.

sculptor.

 

[Disjunto]

apparently my CCC is broken (wont load) so can't help with custom res here :|

 

[str]

I had similar problems (but in Windows XP) with a 20" 1680x1050 when using D-SUB and I managed to force it to work.

In CCC look in the Monitor Properties -> Attributes and disable "Use ... (EDID)..." and manually set the maximum options on that page to 1680x1050 and 60 Hz. Next go to Displays Manager and see if 1680x1050 is now available in the Desktop area box and if it's not try a reboot and hopefully it shows up.