Question about Corsair HX1500i (2023)

In section 2.5 of the quoted manual it says:

"When the system is powered by only one (1) PSU, ensure to use a single rail PSU if you wish to connect PCIE 8-pin connectors to PCIE_CPU_12V_1 and PCIE_CPU_12V_2"

So I do have a 8-pin PCIE cable for PCIE_CPU_12V_1 and another 8-pin PCIE cable for PCIE_CPU_12V_2. These cables should be on the same rail of the power supply. However I don't know if two adjacent PCIE outputs on the HX1500i are on the same rail or not. Apparently one can set this in the firmware but I am not sure If I should start the system as is.

I have been looking at this manual https://dlcdnets.asus.com/pub... and could not find the language you mention. The the board has the usual double 8 pin power connectors on top of the board.. One of them is labeled PCIE_CPU_12V(1)_1 and PCIE_CPU_12V(2)_1 the other PCIE_CPU_12V_1 and PCIE_CPU_12V_2. They both are of the 8-pin types and are labeled on the HX1500i 23 each as PCIe/CPU. Thus when you plug in one of the connectors you supply CPU power for PCIE_CPU_12V(1)_1 and PCIE_CPU_12V(2)_1 simultaneously with one cable and PCIE_CPU_12V_1 and PCIE_CPU_12V_2 with the other.
Make sure to connect the correct cable to each side: the PSU side has one narrow lock pin and the board side a broad lock pin. The motherboard also needs ATX power and this in comprised on the mobo side of a 20 and a 4-pin. I have found that connecting the 4-pin is rather difficult to plug-in.