Found this over on another thread here:
I finally got the Catalyst 6.4 drivers to work on my 3790.
I spent the last 3 days trying to get them to work. I reimaged my laptop with Acronis about a dozen times and rebooted 100+ times trying all sorts of permutations. I was editing .INF files, merging new Catalyst drivers into the old Sager install, and so on. Fortunately, even when the laptop LCD is garbled, the external monitor output works fine, so I could continue to troubleshoot.
It turns out the problem with the newer Catalyst drivers is quite simple.
1. The 3790 LCD requires a 75 Hz refresh rate. Anything else results in a garbled screen. This is unusual in the LCD world, where most LCDs work with a 60 Hz refresh rate. Aggravating the problem is that the Sager LCD doesn't support PnP, so it doesn't tell Windows about the refresh rate requirement.
2. The Catalyst drivers don't have a .INF entry for 1680x1050, so Windows won't recognize that as a supported resolution once you install the Catalyst drivers. You can't select it in the Windows Display Properties. You can force it from the Catalyst Control Center, but that only works until you reboot. When you reboot, Windows resets the resolution.
What happens when you install the newer Catalyst drivers and reboot? Windows doesn't support the 1680x1050 resolution and it falls back to a lower resolution with a 60 Hz refresh rate, and the LCD is all scrambled. Even if your LCD isn't 1680x1050, I think the first post-install boot defaults to a 60 HZ refresh rate for safety reasons, which doesn't help us at all.
While I didn't follow the exact steps below (my config is working now and I didn't want to reimage yet again to check it), here's a fix that should work:
1. Install .NET Framework 1.1. The Catalyst Control Center requires this and it won't work if you only have .NET Framework 2.0 installed.
2. Get the latest ATI mobility drivers here: http://www2.ati.com/drivers/mobile/atimcatw.exe
3. Install the latest drivers, but DON'T REBOOT.
4. Download RefreshForce here: http://www.pagehosting.co.uk/rf/
. It's a great little utility that updates the Windows registry so your display drivers always use whatever refresh rate you specify. You can also use it to add additional resolutions.
5. Run ReForce.EXE. Now you have to find the correct monitor registry entry to modify. It's a bit tricky because every display device gets a monitor entry, but you need to find the one for the built-in LCD. Look for one that's labeled [ACTIVE]. In my case there were three [ACTIVE] entries, but the entry ID I needed was labeled MS_0000. Click the Auto Populate button. This should fill in all the supported resolutions and refresh rates. Change all refresh rates to 75. If you need to add 1680x1050, do it and set it to 75 too. Apply the changes.
6. Reboot. If you chose the right monitor to modify, everything should look fine.
I hope this works for you. Let us know if it does.
Might help someone else. Gonna try it out myself.