Two identical WD3200JS SATA2 disks works differently?

Hi! I purchased my second WD3200JS two days ago, because I already had a same one. So I decided to connect them in RAID, but before that I tried them separately. Both drives are working fine, but the new one (WD3200JS-60PBD0) is AUTO set by the BIOS for CHS, and recognized as only UDMA-5. The old one (bought 2 months earlier, WD3200JS-00PBD0) is working LBA, and UDMA-6. My MB is ASUS A8N-E, and I don't know why is the difference. Tried connecting the drives on SATA connector in every possible way, but the situation is the same. Tried some HDD tools for setting the UDMA speed, but for the second drive every one determines the UDMA-5 as maximum. I didn't try the RAID 0 yet, it would probably work, but I don't understand why are the two identical drives recognized differently. Both drives perform equally, it is not a problem.

:?:

Any ideas?

You may want to try CONFIG command in MHDD (to switch DMA modes).

I would just forget about that though

I wanted to try, but MHDD says the maximum UDMA I can set for that disk is UDMA-5. It looks like it is set by WD to that value, and I can't go beyond. (WHY is the another UDMA-6 ?)
TODAY I will try the disk on other MB to eliminate the possibility of motherboard or SATA controller error.