Gigabyte GA-E7AUM-DS2H - 2 of my 3 hard drives are very slow

Hello forum friends.

I recently built the following HTPC:

Motherboard - Gigabyte GA-E7AUM-DS2H with integrated Geforce 9400
CPU - E5200 wolfdale, R0 stepping
Memory - G-skill 4 gb ddr2-800
Hdrives - Three samsung spinpoint 1.5tb F2EG 5400 rpm SATA drives
Optical - Sony optiarc dvd/cd burner
Case - Cooler master sileo 500
PSU - Rosewill rp500-2
CPU cooler - Arctic cooling freezer 7 pro
OS - Win XP

Out of curiosity, I downloaded HDTune 3.10 and HD Tach to see the data transfer speed of my hard drives.

One registered appox 90 Mbytes/sec avg speed but the other two averaged only 7.5 Mbytes/sec. - less than 1/10th as fast. I get basically the same results every time I test them and I cannot understand why one works fine and the other two do not. Anyone have any ideas?

I would just like to understand what the problem is and how I could correct it as transfers to and from those drives are atrociously slow.

Thanks,
David

Where have you connected them? - They want to be on SATA2_0, SATA2_1, and SATA2_2; page 27 of your manual states: "Due to a chipset limitation, the SATA2_3 and SATA2_4 connectors only support AHCI/RAID mode"; if you have 'em on these connectors without AHCI 'pre-load' drivers in, I'd be amazed that they work at all...

Have you swapped the drives around, to verify whether the problem 'follows the drives', or 'remains with the channel'?