I've been researching a replacement for my aging Belkin F6C-1100 UPS. In reading the reviews and user comments I found one thing in common. Apparently, according to the various vendors, active-PFC PSUs do not work with simulated sinewave outputs when the UPS is on battery. One must have one of the more expensive UPS models with pure sinewave output. I have confirmed this with APC, Cyberpower, and Antec. I have two systems with their Neopower PSUs. I am waiting for response from Tripp-lite. Cyberpower did say they will have new, reasonably-priced UPS systems next year that will have a trapezoidal simulated sinewave that would be compatible with active-PFC PSUs.
Anyone have any experience with this or other comments?