Common ground it not the purpose of that splitter. The splitter provide a "power good signal" from the motherboard to both PSU's, a green light so to speak. Without this power good signal, the PSU's would shut down almost immediately after supplying power to the motherboard. The power good signal is what keeps the power supplies functioning. If the motherboard senses a problem, it will not provide a power good signal.
The power supply may not function, if there is a problem internally with the power good sensor circuit. I had a power supply go out on me and without knowing for sure, I suspect this circuit.
I would say it is very safe seeing as there are cases designed to support two PSU's.
@cliffordcooley hit the nail on the head as per usual, its safe and does not make any unusual problems. I know plenty of people who run dual PSU's on machines because of their setups but for me personally I prefer just one very powerful PSU instead of 2. But its safe, you do not really gain any risks associated with dual PSU's more than just with one other than more of a chance of one failing since your running two.
Something you might want to consider is the max Watt ofyour dual system, as a normal house power outlet cannot suppy more
Than 15A120V RMS,which is1800w
My comment is truefor north amarican electricity
hmm; A standard wall outlet is 15A, but 20A are not rare at all. The power panel will have the rating of every breaker on the toggle.
On a standard 15A outlet, both tangs are vertical, on a 20A, one is shaped like a sideways 't'
Interesting, I didn't know that a some special outlet could output up to 20A, thanks for information.
But my point is, a lot people don't know that power outlet have limit. And a power outlet is rarely alone on its power line. Which means, its limit is certainly under 1800W RMS (or under 2400 for the 20A case).
Last thing, all you need for your system to start is the power-good signal through the ATX24 cable. And yes it requires a common ground for your PSUs to send this signal.
But, you do not need this so called ''Vantacor Dual PSU Adapter Cable 24 Pin 2-way'', save your $$$ because all electrical devices classified as CATII and + are supposed to be grounded on their case. So PSUs ground are attached to their case and motherboard ground is attached to the computer case via its screw. So if both(or more) PSUs are in the same computer case ex ''Antec eighteen hundred'', you do not need a special cable, if they are not, you could take a cable, any cable grade, ex: AWG24, AWG14, etc, and solder/screw it to the second PSU case AND motherboard base via one of its screw. as I've mentioned, you do not need a spacial grade of electrical wire since there wont be any current in this cable, but their respective ground will be the same.
you do not need to care about the second psu power-good signal, your motherboard will receive the first one, and will start.
you should wear safety boot and glasses when doing your experiment on PSUs since AMP can be very high on output side.
sorry if my English is bad
Student Computerized System Tech
I have three PSU's powering my quad R290X machine and as Cliff mentioned they only require a 'power good' or 'wake up signal' from the BIOS. I don't know how much you are pulling under load but I have 2.2kW total or 180A so I put PSU #1 and 2&3 on different circuits. They can be hard to find but I recommend finding a good 18A cord (no more than 6 ft)