Acer Altos 500 Series User Manual page 93

Maximum Sync Transfer Rate
This option determines the maximum synchronous data transfer rate that the SCSI
controller can support. The SCSI controller supports rates up to the UltraWide
SCSI maximum of 80.0 MBytes/sec. The default value is 80.0.
In most cases, you can use the maximum value of 80.0. If the SCSI controller is set
not to negotiate for synchronous data transfer (i.e., Initiate Sync Negotiation is set
to no), then the value selected here is the maximum rate that the SCSI controller
accepts from the device during negotiation. (This is standard SCSI protocol.)
Some older SCSI-1 devices do not support
Fast SCSI data transfer rates. This may
cause your computer to operate erratically or
hang if the transfer rate is set too high. Set
Initiate Sync Negotiation to no for these
devices.
Chapter 3 – SCSISelect Configuration Utility 3-13