Hi, please use 750w.

https://dell.to/3CAqrW2 

GPU Card Installation Guidelines

• Ensure that the GPU cable is available.
• The system supports one single- or double-width GPU card in PCIe slot 3.
• Only single-width GPU Q4000 and dual-width GPU Q6000 are supported.
• Systems installed with the double-width GPU card supports only one 5.25 inch removable media storage device.
• The GPU card must be installed on a system with a redundant 750 W AC power supply.
• The GPU card power cable must be connected to the GPU power connector CN11 on the power distribution board.