Summary: Zalman ZM750-HP is an excellent 750 W power supply. It can deliver up to 850 W at 50° C, has high efficiency (up to 90%) even when delivering its labeled power (85% at 750 W), electrical noise level inside specs and outstanding voltage stability, probably due to its thicker wires (16 AWG instead of 18 AWG).
Excerpt: Zalman currently offers five different power supplies that incorporate one or more heat pipes with output capacities ranging from 500W up to 1,000W. The ZM750-HP features a combination of fixed and modular cables, support for dual core CPUs and multiple graphic cards, and it can deliver up to 750 watts of continuous DC output. The ZM750-HP uses heat pipe technology to augment the internal cooling system for increased reliability and to reduce noise.