No. When using the HDI-45 connector, the computer senses the connection and automatically sets aside 640K of DRAM space for monitor support. There is no way to adjust DRAM allocation for monitor support on the following Power Macintosh models: 6100/60, 6100/66, 7100/66, 7100/80, 8100/80, 8100/100, and 8100/110.
If the monitor is connected in another way (through the DB-15 connector on an AV Video Technologies Card, or an VRAM Expansion Card on a Power Macintosh 7100/66 or 8100/80) the 640K of DRAM video allocation will become available for system use.