In your logs I can see you are using the vesa driver. The vesa driver can not use 1680x1050 (it's not part of the VESA specification). Please try the "ati" driver and attach new logs.
In your logs I can see you are using the vesa driver. The vesa driver can not use 1680x1050 (it's not part of the VESA specification). Please try the "ati" driver and attach new logs.