3.3V, 5V and Universal PCI Issues
A "universal" PCI board is compatible with both 5V and 3.3V signaling environments.
GSC's universal PCI boards detect the voltage provided on a dedicated PCI connector
pin (VIO), and configure themselves automatically for the correct PCI bus logic
levels. Although some confusion exists among users regarding the designation
of a PCI board or slot as "3.3V," "5V" or "universal," all of these references
should pertain to the PCI signaling levels (i.e.: logic levels), and not to
a power requirement. To date (through Revision 2.3 of the PCI specification)
all PCI-compliant bus configurations must provide all four power rails, i.e.:
+5V, +3.3V and ±12V. Most GSC PCI based products use the +5V power rail as their
primary source of power. These same products might be designated as "+5V-only"
or "5V/3.3V" or "Universal," depending on their PCI logic level compatibilities.
If the specification for a specific GSC PCI product does not explicitly specify
universal signaling, contact GSC sales for clarification.