With AAM disabled, the Seagate Barracuda ATA IV delivers a WinBench 99 measured access time
of 13.9 milliseconds, down from the 14.8 milliseconds recorded with default AAM settings. Subtracting 4.2 milliseconds to account for the rotational latency
of a 7200 RPM
drive yields a measured seek time
of 9.7 ms- very close to Seagate's claimed 9.5 milliseconds.
As mentioned earlier, SR readers consider a 0.9 ms difference in access time to be significant. The same difference exists between Maxtor's DiamondMax Plus 60 and the category-leading IBM Deskstar 60GXP.
Western Digitial's Caviar WD1000BB-SE turns in a measured access time of 13.5 milliseconds... virtually the same as the standard WD1000BB's 13.4 ms. Subtracting 4.2 milliseconds of latency yields a measured seek time of 9.3 milliseconds, a bit off of WD's 8.9 ms claim.
In theory, changes in access times and/or buffer sizes should yield no significant differences in measured transfer rates. And as expected, the 'Cuda IV with AAM disabled (after all, it's the same physical drive) yields no changes. Ditto for the WD1000BB-SE.
How do these changes translate into Disk WinMark 99 performance?