Western Digital WD2500KS: SATA II Model
All Western Digital disk drives that include KS in their designations offer both 16 MB of on-board cache and a SATA II interface. And with over 150 MB/s of transfer performance, this drive actually outpaces the SATA I speed limit. In any case, a key limiting factor appears to be the memory chips in the cache, because SATA II should enable throughput rates in excess of 200 MB/s.
The performance we measured for this drive outstrips that for the WD2500JD only by a narrow margin, even if performance is tweaked to get as much speed as possible. The primary reason for this phenomenon is the underlying configuration, which is based on three memory modules in both versions of this drive.