Hello everybody,
         Greetings!

                   I am writing the reply of some one's post about the question "If I connect a gpu to a cable pcie of a psu and the riser with a cable of a different psu, can it be a problem?" which is not so much clear question eventhough I would like to try in simple and short as possible as I can.
In my guess, he would like to make a large GPU mining Rig(eg: 9 GPUs) in a single motherboard at that time he should use two Power supply Unit (PSU) for a single motherboard but safety considerations and procedures should follow for the best result like better to use good quality PSU and should use T2PSU adapter of high quality which connects the two PSU in series with the motherboard simultaneously.It does not matter you can use PSU of two different power capacities.At this situation no problem you can do it.I hope you understand.Thank you.