Both the 1200W and 750W Power supplies are supported
The original intent of the 1200W Power Supply was twofold: future 10G-BaseT SKU support and additional power for potential expansion (if needed for potential expansion modules requiring more power). A 750W Power Supply was subsequently designed to support all the N5K-C5020P-BF configurations and provide better power efficiency.
All N5K-C5020P-BF hardware chassis configurations are supported with single 750W PS, dual 750W PS, single 1200W PS, dual 1200W PS or a mix of both power supplies at 100-120V or 200-240V.
Minimum Software for the 750W Power Supply support: Cisco NXOS Releases: 4.1(3)N1(1), 4.0(1a)N2(1a), 4.0(1a)N1(1a)