I upgraded from an RTX 3060 Ti, which used one 8-pin connector, to an ASUS RX 9070 XT Prime OC that requires three 8-pin connectors. My non-modular ASUS TUF Gaming 750B power supply is advertised as having four 6+2-pin PCIe connectors, but it actually provides two separate cables, each with a piggyback 6+2 connector. That means I can only connect the card using two separate cables plus the extra connector on one of them. Some guidance says piggyback connectors should never be used for GPUs, while other people say they are fine with a suitable modern PSU. I am not planning to overclock, but I want to avoid damaging the graphics card, other components, or the cables. Is this setup safe, or should I replace the power supply?
3 Answers
The blanket rule that piggyback PCIe connectors must never be used is too broad. With a quality PSU, a correctly rated cable, and a card that distributes its load normally, one pigtailed connection can be acceptable. However, the power supply's age and quality matter a lot. Check its label and manual for the combined 12 V output and inspect the plugs for looseness or heat damage. Since this is an expensive new GPU and the PSU is older, replacing the PSU is the safest and most future-proof option rather than relying on the absolute minimum setup.
The bigger concern here is the power supply, not simply the piggyback plug. The ASUS TUF Gaming 750B is an older, non-modular 750 W unit, and a high-end RX 9070 XT can produce substantial short power spikes. It may work, but there is less headroom than I would prefer. If you are buying a replacement, choose a current, reputable 850 W unit with enough dedicated PCIe cables and the appropriate modern GPU power support. If you keep the existing PSU, avoid overclocking, monitor for shutdowns or restarts, and stop using it if the connectors become unusually hot or discolored.
A piggyback connector is not automatically unsafe. The warning is mainly about making sure the cable and power supply can handle the load, since both connectors share the same cable and terminals. AMD cards generally distribute power across their connected plugs properly, unlike some high-draw Nvidia cards that made this issue more serious. The 9070 XT's roughly 300–340 W typical draw is within the capability of three PCIe connectors, even with two plugs sharing one cable. Connect one plug from each cable first, then use the piggyback plug for the third connection. Do not use adapters or extension cables, and make sure every 6+2 connector is fully seated.
That is the arrangement I would need: one connector from each cable, plus the piggyback connector from one of those cables. My main concern is whether the 750 W power supply is too old or marginal for transient spikes.