Can I Power an RTX 4080 With Only Two PCIe Cables From My RM850x?
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MellowQuartz42
I upgraded to a PNY RTX 4080, and its included adapter has three 8-pin PCIe connectors. My Corsair RM850x only came with two PCIe cables, so I'm one cable short. I've heard that using the pigtail or daisy-chain connector can cause power spikes, crashes, or overheating, so I'm hesitant to connect all three plugs using only two cables. Is it safe to use the adapter this way, or should I upgrade to an RM1000x?
Answers
You don’t need to upgrade the power supply. Using two PCIe cables, with the daisy-chain connector on one of them, is acceptable for this card. Three separate cables may be preferable, but the RM850x is capable of handling the load when the connections are fitted correctly.
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The advice to never use a pigtail is generally outdated for a quality, modern power supply like the RM850x. In the meantime, connect two separate PSU cables to the adapter and use the additional connector from one cable. Ensure every plug is fully seated and avoid sharply bending the cable near the GPU connector.
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Another option is to buy a compatible Corsair Type 4 PCIe-to-12VHPWR or 12V-2x6 cable. It connects directly from the power supply to the graphics card and lets you skip the adapter. Make sure it is specifically designed for Corsair Type 4 modular power supplies—modular cables are not universally interchangeable.
MellowQuartz42: That sounds cleaner than using the adapter. I was worried about accidentally buying an incompatible modular cable, so I’ll stick to a cable made specifically for the RM850x.
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MellowQuartz42: My RM850x only has regular 8-pin PCIe sockets, not a dedicated 12VHPWR socket. I currently have two PCIe cables connected for my old card, so I’ll need to add the third GPU connection using one of the pigtails or buy the correct Corsair replacement cable.