Identical drives, different results

I have two 10EADS drives that differ only in firmware.   When connected one at a time to a Silicon Image SiL3512 SATA card, the one with firmware 01.00A01 works fine, but the one with 01.01A01 makes Windows XP very sluggish and causes I/O errors.  These are secondary drives; the primary is connected to the motherboard’s controller.

How do these firmwares differ?

It may not be a firmware issue. Instead it could be that one drive has “slow” sectors that require several read retries. A HD Tune read benchmark may show scattered points around the access time graph. Alternatively, try scanning your drives with MHDD or Victoria for Windows. These utilities will identify slow blocks.

Another culprit may be NCQ. Have you tried disabling it, assuming it is supported?

I bought 2 identical drives with differing firmware, neither of which was or is listed as “advanced format”, yet one shows up under the align tools and other drive tools as being advanced format.(512b emu/4096b real sectors). I didn’t get errors though, only horrid performance until I used partitioning tools that took into account the 4096b real sector size. You might download and use both of WD’s alignment tools and see if the slow drives reports as AF. Other than a few MB download nothing to lose for you.