The I128 driver should auto-detect all supported hardware so you needn't have anything other than the Identifier in the Section "Device" of the XF86Config file. When running the XF86Setup or xf86config programs one merely needs to select an I128 card so that the correct server will be used. One need not and should not specify a RAMDAC, clockchip or allow the setup program to probe for clocks. The driver will auto-detect the amount of video ram present.
The following Section "Device" options are supported by the I128 driver:
Will enable 6-bit DAC support.
Will disable all hardware acceleration.
Will enable syncing on green for sync-on-green monitors (these are typically fixed frequency workstation monitors).