Sh0 released a tool for the GP2x that let you test your SD card.

Simple SD Test with hdparm and log to hdparm-log.txt. Copy to SD, run hdparm.gpu … wait and read hdparm-log.txt with the e-book reader.

http://www.gp2x.de/cgi-bin/cfiles.cgi?0,0,0,0,8,1303