I bought this card at Geeks.com for ~$19 shipped. Its manual says "supports SATA data transfer rate of 150 MBps". Obviously, I didn't exepct anything near 150, but was hoping for at least 50 MB, which would at least 2x faster than the internal hard drive on my Dell Latitude D430 laptop. One guy told me that I won't get even 10 MB. However, this guy seemed to use very similar card on his Lenovo, and after some initial trouble managed to get 50 MB rates measured with HDTune tool. I usually use HDTach.
Anyways, I got the card, installed it and connected through SATA II cable to an external 1TB WD10000H1CS WD My Book drive. It's not the fastest drive ever by HDTach on dell desktop with eSATA II ports shows me 140MBps burst and ~70MBps sustained read speeds.
The the card in my laptop shows up as PCMCIA Adapter R/RL/5C476(II) and SCSI/RAID Silicon Image SiI 3512 SATALink Controller. HDTune results are here.
HD Tach reports me 2% CPU utilization, 70MB/S burst and 44 MB/s average read speeds, random access 15ms. I'm quite satisfied with this performance, although it could have been better.
PCMCIA's web site has this theoretical throughput. I'm not sure which one's applicable in my case though:
PC Card/CardBus Throughput
Theoretical maximums are as follows:
16-bit I/O Transfers (255 ns Minimum cycle)
* Byte mode: 3.92 Mbytes/sec
* Word mode: 7.84 Mbytes/sec
16-bit Memory Transfers (100 ns Minimum cycle)
* Byte mode: 10 Mbytes/sec
* Word mode: 20 Mbytes/sec
CardBus (32 bit burst mode)
* Byte mode: 33 Mbytes/sec
* Word mode: 66 Mbytes/sec
* DWord mode: 132 Mbytes/sec
Please note that actual throughput may be substantially less than the theoretical maximums of the interface.