I recently bought an MSI GeForce RTX 3070 SUPRIM X 8GB, but my SeaSonic FOCUS Plus 550 Gold 550W power supply only came with one PCIe power cable. My previous GTX 1650 Super used just one connector, while the RTX 3070 appears to require two PCIe power connections. I bought the power supply secondhand and the extra modular cables were not included. I have checked and there are no additional cables in the box. What exact replacement cable or cables are compatible with this specific SeaSonic PSU? I am trying to avoid buying a new power supply right now, so I want to make sure I do not order an incompatible modular cable or adapter.
3 Answers
Do not buy the cable just because the listing says it is designed for a newer GPU such as a 4070 Ti. GPU compatibility and PSU-side compatibility are separate issues. The cable must match the exact modular pinout of the SeaSonic FOCUS Plus 550 Gold. Also, avoid generic modular cables and do not try to force a connector into place. A properly labeled replacement PCIe cable for that PSU, or a complete compatible cable set from a reputable seller, is the safe option.
The graphics card needs two separate PCIe power plugs, typically two 8-pin connectors, rather than a special 12-pin cable. The important part is that the cable connects to the PSU's PCIe sockets and is made specifically for the SeaSonic FOCUS Plus series. Modular PSU cables are not universal, even when the plugs look similar, so do not use a random cable from another brand or model. Look for a replacement SeaSonic-compatible PCIe cable or a purpose-built cable from a reputable cable manufacturer, and verify that it lists the exact FOCUS Plus model before buying.
I found another cable that looks like it might fit, but I was not sure whether cables for newer graphics cards would work with this PSU.
The 550W rating may be enough for a stock RTX 3070 system, but the power supply still needs the correct connectors and should be in good condition. Since it was bought used and the original cables are missing, be especially careful: using the wrong modular cable can damage the PSU or graphics card. If you cannot confirm the replacement cable's pinout and model compatibility, replacing the PSU is safer than experimenting with an unknown cable.
An adapter intended for a different graphics-card power connector is not automatically suitable here. Confirm the card's required connector type and the PSU model before ordering.