What's the jumper "enable 1.5GB PHY" on a Western Digital hard disk?

Question

I've got a new hard disk. On the label there is a description of the jumper settings:

One of them is:

Jumpered pins 5 and 6 enables 1.5GB PHY

What does PHY stand for?

Answer 1

It's SATA II disk, right?

And if you put jumper on these pins HDDs will be SATA I.

It's there for if your motherboard doesn't support SATA II.

Answer 2

PHY stands for "physical layer". By jumpering pins 5 & 6 will cause the drive to go into a legacy 1.5 Gbit/s mode, rather than its default 3.0 Gbit/s mode. Check out the Wikipedia article on SATA for a bit more info.

Answer 3

By jumping the two pings, 5 and 6, you limit the transfer rate to 1.5 GB/s.

PHY is simply the physical layer in question, between the drive and cables/transfer.

Take a look at Wikipedia's page on SATA throughput.

Answer 4

I bought the same disk 2 days ago. What everyone else says is right, jumpering those pins will limit the transfer rates to 1.5Gb/s rather that the 3Gb/s it is capable of.

Also,
Pins 1 & 2 enable Spread Spectrum Clocking which reduces the drives electronic noise, at the cost of some performance.
Pins 3 & 4 enable Power-Up In Standby (low power mode). Your motherboard needs to support this. I couldn't find any way in Vista to get my external drive out of standby.