I have a WD6402AAEX disk as my primary drive. Speccy S.M.A.R.T. data reports it as having:


16MB cache

16 heads

This can’t be right, the drive should be 7200 RPM, 64MB cache, as for the advertised specs.


Try a different utility, such as HD Sentinel.

To see the RPM graphically, run HD Tune’s read benchmark.and examine the spread of data points in the access time graph. A 7200 RPM drive will have an access time graph that is 8.33 msec wide (= the time for one complete revolution), whereas a 10,000 RPM drive will have a 6ms graph.

AFAIK, the ATA standard still does not provide a way for a drive to report more than (32MB - 512 bytes) of cache. Therefore your drive should actually be reporting 0MB.

See http://seagate.custkb.com/seagate/crm/selfservice/search.jsp?DocId=203631

As for the heads, 16 is the number of “logical” heads and has no relationship to the actual number of physical heads.