Here are the directions for using NTtune:

In order to use NTtune successfully you must be the Administrator. If you are not, log out and log back in as the Administrator. NTtune is executed under the command prompt window (ms-dos) of NT/W2K. The NTtune arguments are (1) the SCSI adapter symbolic driver name you wish to target, (2) the maximum number of 4 kbyte chunks you wish to accomplish in a single SCSI transfer, and (3) the maximum number of simultaneous requests that will be allowed on the targeted SCSI adapter. If you are unsure of the SCSI adapter's symbolic name simply go to the device manager under W2K and check the properties of the SCSI adapter. Within NT go to Settings - Control Panel - SCSI Adapters and again view the properties of the desired adapter. As an example, most of the Adaptec 294x/394x series adapters use AIC78XX.SYS as the system driver. The NTtune arguments to increase a single SCSI transfer up to 640 kbytes (160 x 4kbytes) and handle 32 simultaneous SCSI requests would appear as follows ....

NTtune aic78xx 160 32

(as you may notice, the .sys is understood and should not be included on the command line)

You must reboot in order for these settings to take effect!To revert the adapter back to its default settings ( 16, 16) all you have to do is issue the command

>NTtune aic78xx 16 16

and then subsequently reboot.