I recently bought an MSI GeForce RTX 3070 SUPRIM X, but my power supply only came with one PCIe power cable from when I was using a GTX 1650 Super. The graphics card appears to need two PCIe power connections, and I don't have the second cable.
My power supply is a Seasonic FOCUS Plus 550 Gold 550W unit, purchased used, so the original extra cables were not included. I have already checked inside the case and confirmed there are no spare cables. I need help identifying a safe replacement cable that is specifically compatible with this power supply. I don't know much about modular PSU cables and want to avoid buying the wrong type or damaging the components.
I would prefer not to replace the entire power supply right now, since most of my budget went toward the graphics card. Can anyone point me toward the correct cable or explain exactly what I should look for?
3 Answers
Before buying anything, verify the connectors on the graphics card. This model normally uses two 8-pin PCIe power plugs, not a single 12-pin connector. A modular PSU cable must match the exact Seasonic Focus Plus series and the PSU-side pinout, so do not use a cable advertised only as compatible with another brand or model. The safest option is an original Seasonic replacement or a cable specifically listed for the Focus Plus platform by a reputable cable manufacturer.
The adapter shown is not automatically safe just because it is labeled for a newer graphics card. GPU-side connectors can look similar while the modular end that plugs into the PSU is wired differently. Never mix modular cables from different power supplies, and don't buy a generic cable unless the listing explicitly confirms compatibility with the Seasonic FOCUS Plus 550 Gold. Also make sure the cable provides the required two 8-pin PCIe connections, using separate PSU outputs when possible.
A graphics-card extension or adapter only changes the connector arrangement; it does not solve the missing PSU-side cable. The important part is finding the correct Seasonic modular PCIe lead.
Your 550W supply may be enough on paper for a stock RTX 3070, but it is close enough that the power supply should be in good condition. Since the unit was bought used and the original cables are missing, replacing it later with a complete, quality unit would be sensible. For now, use only a verified compatible PCIe cable and connect both plugs on the card; do not try to force a CPU/EPS cable or improvise a pinout.
I checked the card and it has two separate connectors. I wasn't sure whether a cable made for a newer graphics card would also work with this power supply.