Rick McLeod <mcleod@esprit.esd.sgi.com> writes:  This depends on the
  SGI monitor.  PCs want multifrequency/ multiscanning/multisyncing
  monitors.  Earlier SGI platforms supplied fixed frequency or dual
  scan mode monitors.  These will not work on PCs.  Some current SGI
  machines (Indy, Indigo2, Onyx) ship with multiscan monitors.  These
  will most likely work with a PC, but make sure that the monitor gets
  the proper sync signal.

  Clinton Keith <clint@art.ray.com> adds his implementation details:
  The GDM-17E11 works on my PC with a Diamond Speedstar 24x.  I used a
  VGA connector that brought out the RGB V and H sync lines from the
  24X into BNC connectors (commonly avaliable at a local computer
  store).  I connected the V sync H sync and Green lines together and
  connected this line and the Red and Blue lines to a BNC-to-DB13W3
  connector (bought a workstation supply vendor) which went to the
  monitor.

  I then set up the 24X to provide -/- sync voltages and selected the
  highest vertical and horizontal scan rates I available.
  Unfortunately, the monitor refused to display 640x480 (pride?) but
  did well at 800x600, 1024x768 and 1280x1024.  There was a slight
  greenish tint to the black areas of the screen.  It seems as though
  connecting the sync lines to the Green may have added a DC bias, but
  the effect is minor.

  Companies which make graphics cards which drive SGI monitors (both
  fixed- and multi-frequency) on PCs include:

  PCG			800-255-9893 or 310-260-4747
      Ask for Ben at extension 747
      photon@earthlink.net
      http://www.photonweb.com/
  Mirage		800-228-3349 or 310-301-4545
      http://www.mirage-mmc.com
  Software Integrators	800-547-2349
      http://www.si87.com/

  The monitor that SGI ships with the O2 has an HD-15 Super VGA-type
  connector on it and can be connected to most SVGA boards.