[Trisquel-users] Re : Trisquel 8 install didn't detect my monitor, gave wrong resolution.

[lcerf]

The last line of lspci's output confirms what you wrote: your computer has a  
rather uncommon SiS video card.  It would therefore not be surprising if  
Trisquel's kernel configuration mistakenly does not fully support the card  
and that you are the first one to face the problem.  Again, I would try a  
kernel on https://jxself.org/linux-libre/ and see.