FC4 + SyncMaster 171S + intel 815 card problems

[C.F. Scheidecker Antunes]

Hello all,

I've just replaced my monitor to a SyncMaster 171S LCD one and upgraded 
my box to FC4.
Although it is properly detected it does not work well. If I am to use 
the 1280x1024 resolution, which is the standard for this monitor, I have 
the picture fiting perfectly but I also have vertical lines as it seems 
the frequency is not ok. Well, the monitor is 1280x1024 at 60Hz with 
horizontal frequency of 30-81 KHz and Vertical frequency of 56~76 Hz. 
I've tried to mess with X config file as well but I still have the same 
problem. If I try a better resolution say 1400x1050 the lines are no 
longer there but the monitor image does not fit the screen verticaly and 
there is no way on this monitor to change the vertical size, only the 
horizontal.

I have another computer, a Presario 6000, with the same SyncMaster 171S 
monitor and a S3 ProSavage KM133 chip. It works perfectly with 1280x1024 
and the setup FC4 automaticaly chosen for it.

What shall I do with the i815 video card machine? Any ideas other than 
putting another card?

Thanks in advance,

C.F.