Setting DPI is Suse

I feel that Fonts in Suse are big, so I decided to set dpi to 75. I modified kdmrx and Xservers to set it but it did't worked. It only works when I modify xorg.conf. Here is what I did: Section "Monitor" DisplaySize 427 320 It was 320 240 before. Is this a bug ? Do you know a better way to do it ?