Can one use a "SATA II" hard disk that has no jumpers and it configured for 3 Gbps mode (or AHCI?) in the PowerMac G5 (eg, Samsung, where configuring to 1.5 Gbps can only be done via a Windows tool).
The question is if the drive has to be set at 1.5 Gbps or the Mac will autoconfigure it. There are drives which come configured at 1.5 Gbps, even if they support 3 (the right thing to do).
I used 3gbps drives in my G5 and had a setting for either one. I used the 3.0 setting and never had any problems. The controller will just work at 1.5gbps and not the 3.0 even if the jumper is set for the faster speed.