I also use SIS chipset M650 on one of my machines, and your log is very similar to mine and has the same error messages, which are largely unimportant. I have found that it does seem to set the resolution fine when
xrandr is used. Type just
xrandr to see the list of resolutions and choose one, for example, 1280x1024 and enter
xrandr -s 1280x1024. That should work because your log notes that
xrandr has been enabled.
To find out exactly which chipset you have got (I know you have posted a rough range of models from
sudo lshw -class video
I think it probably should be the SiS 661FX; now refer to Thomas Winschofer's guide for driver options particular to your chipset. The so called premium version of the driver has been discontinued and most of its features integrated in the standard version, so I don't think compiling the source code of the premium driver (which is now available) would help. As it is noted on the site there are no specific bug fixes for your issue in the changelog. I hope some of this information is useful, nevertheless.