text: Q:
  
  What impedances do graphics cards expect on H-Sync and V-Sync for VGA monitors?
  
  I have a graphics card for a laptop whose driver kills itself if it runs for longer than two minutes with no external monitor attached. To solve that, I decided to make a sort of dummy plug that would be detected as a monitor by PC. 
  I have managed to find out what impedances video card  expects for most of the pins, but for H-Sync and V-Sync, Google brought up numerous conflicting answers, mostly from people who are guessing. 
  
  A:
  
  According to the VESA Plug and Display standard, which uses compatible electrical signaling for analog video, the host is supposed to detect a minimally-capable monitor by looking for 75 Ohm termination on the video lines. Anything beyond basic functionality is determined by reading EDID information over the I2C lines. 
  Because EDID is so old, the video card may not even bother checking for a monitor without it. You could probably fool the video card into believing a monitor with any desired capability is present with an appropriately programmed I2C EEPROM or microcontroller.
  
  