Re: 1680 x 1050 native res not working
Things are not as they were in the past...
Before, you could tell the X server what to do. You created a modeline, tell the X server that this is the timing it has to use, and it would work fine.
Then came the days of "plug and play". First in Windows, but it has invaded Linux as well. Now you see log lines like "screen resolution determined to be 1280x1024" which is clearly incorrect. Maybe the monitor provides incorrect EDID data, maybe the driver does not read it correctly.
Things go worse from there: it decides your modeline is invalid, discards it, then tells you it has no mode for the resolution you want and inserts its own default mode which is the 1280x1024 you see.
How we got in the state where the driver "thinks", and even worse: thinks it should trust EDID data more than configuration file options, is unclear. But that is where we are now.
Fortunately there still are configuration options that turn off this behaviour.
You can try adding this option for the device:
Option "ModeValidation" "NoDFPNativeResolutionCheck"
There are also other options. Read the driver README.