So , from what EJ says
Yellow slots:
With 2T9 equipped, if a yellow socket has a 4 STR bonus or better, you can gem one of these (usually inscribed). Once you replace 2T9, it's recommended that you just gem everything pure STR.
But from RAWR i notice a DPS LOSS if i gem everything in STR instead of 10str 10 crit in yellow sockets with 4STR bonus or better.
I am 4 PC T10 atm.
Can someone clarify this please ?