I'm putting together a used PC for a friend with an NZXT 750W Gold power supply and an RTX 2080 Super. The graphics card needs two 8-pin PCIe connectors, but the PSU only came with one PCIe cable. That cable has two 6+2-pin connectors on a daisy chain. Would it be safe to use both connectors from that cable, or should I use a dual-Molex-to-8-pin adapter for the second connection? The PSU has only one Molex cable, though it has enough plugs for the adapter. I've heard Molex and similar adapters can be a fire risk, so I'd rather avoid them if possible. I'm also aware that the ideal setup is two separate PCIe cables and want to know whether the daisy-chained cable is acceptable here.
3 Answers
Do not use a Molex-to-PCIe adapter for this card. Those adapters add another weak connection point and may overload the wiring or connectors. Use the two 6+2-pin plugs on the proper PCIe daisy-chain cable if the cable is an original, compatible NZXT cable and is in good condition. A 750W quality PSU should generally handle an RTX 2080 Super this way, although two separate PCIe cables would be preferable if the PSU supports them.
A normal PCIe power cable with two daisy-chained 6+2 connectors is designed for situations like this. Connect both plugs directly to the graphics card and avoid mixing in Molex or SATA adapters. The card’s total power comes from the motherboard slot and both PCIe connectors, and the cable is rated for the expected load. If you notice excessive heat, discoloration, or loose connectors, stop using it.
Make sure you do not buy a random modular replacement cable just because the connector fits. The PSU-side pinout is not universal, even between models from the same brand. Replacement cables must be confirmed as compatible with the exact PSU model. If you want the most conservative setup, buy a second genuine compatible PCIe cable or replace the PSU, but a proper factory daisy-chain cable is still a much better choice than a dual-Molex adapter.
The cable is the original one that came with the PSU, and it splits into two 6+2-pin connectors. I was mainly concerned that the GPU’s slot provides another 75W and that the cable might be overloaded, but it sounds like the daisy chain is still safer than using a Molex adapter.