VGA Card Informations

VGA frequencies in different modes

From: steveq@syd.dms.CSIRO.AU (Stephen Quigg) Newsgroups: sci.electronics Subject: Re: VGA startup board/monitor sync? Date: 14 May 91 23:06:07 GMT Organization: CSIRO Maths and Stats & Applied Physics, Sydney, Australia 

The VGA board tells the monitor what to expect by the polarity of the horiz. and vert. sync signals. Here's what an NEC MultiSync 2A sets up to.

Vert Res.      Horiz Freq    H Sync    Vert Freq    V Sync                             Polarity               Polarity  350 lines      31.5 kHz      pos       70.07 Hz     neg 400 lines      31.5 kHz      neg       70.07 Hz     pos 480 lines      31.5 kHz      neg       59.95 Hz     neg 600 lines      35.2 kHz      pos       56.24 Hz     pos 

Your problem is probably one of the following; 1. You are trying a mode your monitor won't support. 2. Your monitor is out of adjustment. 3. Your monitor is faulty. Possibly, the card or monitor is not "playing the rules", eg monitor expects one set of sync rates according to the sync polarities, and the card is sending out another (unlikely but...)