The Z600 has USB 2.0 ports only, no USB 3.0.
Blue P27 is a single USB internal port. It follows the standard USB pinout: Pin1 = 5V USB power, Pin 2 = Signal D-, Pin 3 = Signal D+, Pin 4 = Ground, Pin 5 = empty = key.
- Blue P26 is a dual port USB 2.0 internal header. It has the standard USB dual pinout, similar P27 above (with one port on a row of pins on one side, and the port other on the other row of pins), with the exeption of pin 10 being a cable detect pin. Pin 9 is a key. Most third party adapters will fit on this header.
- Yellow P24 is a 14 pin header, with 3 USB 2.0 ports, all routed to the front panel. Pins 1 to 10 follow the P26 pinout, with the extra pins were added to add the third port to the front panel. Simple.
The Z620 is very different. It has both USB 2.0 and USB 3.0 ports routed to the front of the system. The Z620 has a separate USB 3.0 controller IC, which is not on the Z600.
- P27 pins 1, 3, 5, 7, and 9 (one side of the header) are a single USB 2.0 port that routes to the USB 2.0 port onthe front panel (with cable detect on pin 9)
- P27 pins 2 and 4 (orange) are +3.3V power, and pins 6 and 8 are Ground. Do not connect a USB connector or adapter to these pins!
- P29 is the blue 20 pin USB 3.0 connector. It follows the industry-standard pinout, so, in theory, one could connect an adapter to this and use it for another USB 3.0 device or different panel.
HOWEVER, KEEP THIS IN MIND: The Z620 front I/O USB cable is an active cable, with USB 3.0 redriver ICs in them. That is the big square in the middle of the cable. Redrivers are needed to provide USB 3.0 signal integrity. The orange power wires on P27 are used to power these redrivers.
- If one does not use the Z620 cable, and runs ordinary cables from the USB 3.0 connector P29, USB 3.0 will (very) probably be intermittent, flakey, and unreliable. That is why HP put active redrivers inside the cable, to make them reliable.
USB 3.0 is 5Gbps, which is really high speed and requires careful system and cable design.
I am not sure what you are trying to do with the Z600. Are you trying to put in a USB 3.0 front panel, and connect this to an add-in expansion card in the Z600? If so, long cables (long is greater than 4 inches) will probably (certainly?) have an unreliable connection. I strongly discourage doing this.