Which features does jumper OPT1 and SSC in WD blue?

In instructions have details about jumpers.
Jumper 1-2 enable Spread Spectrum
Jumper 5-6 enable PHY,

Which features are Spread Spectrum and PHY ? Both are good features ?
Not information about Jumper 3-4 in documentation. Enabling jumper 3-4 does what feature ?

Thanks for reply.

Hi @aug,

Please refer to the article of How to enable and disable PM2 (power management) on WD SATA drives:

For more information, please contact the WD Technical Support team for best assistance and troubleshooting: