Nothing is wrong. You are probably connected to the Macintosh video port via an adapter. The Sony 17sfII monitor's maximum PC resolution is 1280x1024; the maximum Macintosh resolution is 1024x768. If you would like to show 1280x1024, you must connect to the VGA port. Following is a list of Power Computing machines and their available VGA ports.
Machine VGA port
----------------------------------------------------
Power 100/120 HPV card (optional)
PowerWave ATI card
PowerCurve Built-in
PowerCenter Built-in
PowerTower Built-in
PowerTowerPro IMS Twin Turbo card
PowerBase Built-in
PowerCenter Pro Built-in
Machines Affected: All