If your board is listed, edit file /etc/openwin/server/etc/OWconfig
and change defdepth="8" to defdepth="16" in it.
Also, values for MaxPClk for some cards are way too low in 16-bit and 24-bit
modes in file /usr/openwin/share/etc/devdata/SUNWaccel/boards.
But if you want to change this, you are doing it on your own risk.
Some applications hang on 16-bit colors.
The CDE logo that is displayed after one logs in is a bit-mapped
grayscale image(?!), but everything else should work just fine.
[Thanks to Aleksandar Milivojevic, by way of John Groenveld]
[an error occurred while processing this directive]