I'm putting together my first PC in several years. The system is currently running on the CPU's integrated graphics while I wait for an Intel Arc B580 GPU. My MSI MAG Mortar mATX WiFi motherboard has an additional PCIe power header, and I'm unsure whether it needs to remain connected once the graphics card is installed. Should both the motherboard PCIe header and the GPU receive power, and which modular PSU cables should I use? I'm also unsure whether both connectors on the motherboard's split CPU power cable are required for a Ryzen 5 9600X, or whether one is enough.
3 Answers
For the CPU, one 4+4 EPS connector in the primary CPU header is normally sufficient for a Ryzen 5 9600X. The second CPU header is mainly for higher-power CPUs or overclocking, unless the motherboard manual specifically requires both. Use the main CPU1 header shown in the manual.
The motherboard’s extra PCIe power header is auxiliary power for the expansion slots. It isn’t a replacement for the graphics card’s power connector. You can leave it connected if the motherboard manual recommends it, then connect the B580 separately using the appropriate PCIe cable. Don’t move the motherboard cable over to the GPU.
That was my confusion—I only saw two modular sockets labeled CPU/PCIe and wasn’t sure how both the CPU and GPU could be powered.
Check exactly which cables came with your RM650e. If it includes a genuine 12V-2x6 cable and the graphics card supports that connection, you can use it with the proper PSU-side cable. Otherwise, power the B580 with its standard PCIe 6+2 connector or connectors. Never substitute a random modular cable, and don’t force a connector into a socket just because the labels look similar.
The manual says either CPU header is equivalent, so I’m using CPU1 and leaving the second one empty.