I'm upgrading an older PC with a Gigabyte GTX 750 Ti 2GB. It has a UNYKAch ATX 500W model 52099 power supply, but the PSU doesn't include a native PCIe 6-pin connector. There is one unused SATA connector and one unused Molex connector available. The graphics card is relatively low power, but this particular model requires an auxiliary 6-pin connection. A local shop recommended replacing the PSU instead of using an adapter, mainly because of safety and reliability concerns. If replacing the PSU isn't immediately possible, would a single Molex-to-6-pin adapter, a dual-Molex-to-6-pin adapter using separate PSU cables, or a SATA-to-6-pin adapter be the least risky option? I'm especially interested in long-term experiences with overheating connectors, instability, or other problems.
4 Answers
I would avoid the SATA-to-6-pin option entirely. SATA power connectors were designed for drives and have less comfortable power-handling capacity for this kind of load. Don’t use a splitter or overloaded cable if you can avoid it, and don’t overclock the card while using an adapter.
Many GTX 750 Ti cards draw most of their power through the motherboard slot, and the versions with a 6-pin connector usually only need modest additional power. That means a correctly wired Molex adapter may work in practice, and some people have used this setup successfully. However, it doesn’t eliminate the risks of a poor-quality or aging PSU, so I would treat it as a temporary workaround rather than a permanent solution.
If an adapter absolutely has to be used, Molex is generally preferable to SATA. Use a proper dual-Molex-to-6-pin adapter connected to Molex plugs from separate PSU cable runs, and avoid sharing those plugs with other devices if possible. SATA power connectors and their small contacts are not a good choice for supplying the current a graphics-card connector may draw, even with a low-power card.
Replacing the PSU is the safest and most sensible option, especially if the existing unit is old or of questionable quality. The wattage printed on the label matters less than the PSU’s build quality, wiring, and ability to deliver power reliably. A new unit with a native PCIe connector avoids putting extra stress on adapters and drive connectors.
Using two Molex connectors from separate cable runs spreads the load better than relying on one connector, but it still isn’t as good as having a native PCIe cable. Make sure every plug is fully seated and stop using it if any connector or cable becomes warm.