Is a 750W PSU enough for a Ryzen 7 7800X3D and RX 9070 XT?

Yes, a good-quality 750W PSU should be enough for those parts. Look for an 80 Plus Gold unit from a reputable manufacturer, preferably a fully modular model with modern ATX 3.0 or 3.1 support.

750W is generally fine, but an 850W model can be worth considering if the price difference is small. It gives you more headroom for extra drives, accessories, or a future upgrade.

Don't choose a low-quality power supply just to save a little money on a high-end build. Check a reputable PSU tier list and prioritize build quality, warranty length, and the proper graphics-card power connector over the efficiency label alone.