Very Computer

I nave several sun servers and 3 of them are equipped with Sun PGX32 PCI
graphic cards.
All servers are connected to one BlackBox ServManager and 50f sun coax
cables,
but I cant see anything from these with PGX cards.
May be there is a problem with a resolution or with the video frequency
range,
because I receive a message:
"Out of scan range"
The default resolution is 1152x900x66
Do you know what type of resolution and/or video frequency range  I need
to set?
Or any other ideas?

Thanks
Lubo