from the web http://www.cremax.com.tw/
MB559US-1S 所使用的晶片為 Sunplus SPIF215A 晶片組
傳輸速率 eSATA：3 Gb/sec., USB2.0：480 Mb/sec

from http://w3.sunplus.com/ShowFeature.asp?body=SPIF215A
the SPIF215A chip support Serial-ATA generation 1 transfer rate of 1.5Gb/s

Oh... which one is right?