I'm putting together a new system with a Ryzen 7 9800X3D, XFX Mercury RX 9070 XT OC, MSI X870E Gaming Plus motherboard, 32GB of DDR5-6000 memory, Corsair RM850x power supply, Corsair Titan 360 RX LCD cooler, and Corsair Frame 4500X LX-R case. The GPU needs three 8-pin PCIe connectors, while the iCUE Link hub requires a 6-pin PCIe power connection. After reserving two EPS cables for the CPU and three PCIe cables for the graphics card, I don't have another modular PCIe socket available on the PSU. Can I use the RM850x's 12VHPWR socket with a Corsair 12VHPWR-to-2x8-pin cable for part of the GPU power, alongside another PCIe cable? Also, does the CPU really need both 8-pin EPS connectors, and is there a safe way to power the iCUE Link hub without upgrading to a 1000W PSU?
4 Answers
You can also power the GPU using two separate PCIe cables and the additional 6+2 connector from one of those cables, provided the GPU manufacturer and Corsair’s documentation consider that arrangement acceptable. Using separate cables where possible is preferable, but the exact cable layout matters less than using correctly rated, compatible PCIe cables and avoiding any CPU/EPS cable on the GPU.
If you want to keep the iCUE Link system, use the spare modular socket freed by running only one CPU EPS cable, then connect the hub with the proper PCIe power lead. Don’t assume a SATA adapter is safe just because the connector can be adapted. The RM850x should have enough wattage for this build; moving to 1000W isn’t necessary solely to gain another connector.
The Ryzen 7 9800X3D normally only needs one 8-pin EPS connector unless you’re doing extreme overclocking. You can leave the second CPU socket empty. However, EPS/CPU cables and PCIe cables have different pinouts—never substitute one for the other, even though the plugs look similar. Use a genuine Corsair replacement cable or one explicitly confirmed to support your PSU revision.
The 12VHPWR output is intended to provide substantial power, so a compatible Corsair cable that converts it to two 8-pin PCIe connectors can handle two of the GPU’s connectors. You could then use one regular PCIe 6+2 cable for the third connector. Make sure the cable is specifically compatible with your exact RM850x model and is fully seated at both ends.
That makes sense. I wasn’t sure whether the second CPU connector was required, so freeing that modular socket should solve the hub-power problem.