What jumpers do in WD2500AAKX?

Today i saw juper settings on my WD2500aakx, but i can’t find any explanation for what purpose they. On drive’s sticker writen: jumpered pins 3-4 enables PUIS.ping 5-6 limits PHY to 3Gbps. What is it meaning? Thank you for any help.

Hello,

Maybe this link will help.

http://support.wdc.com/KnowledgeBase/answer.aspx?ID=981