I have both the APC 800va BackUPS RS and the Powercom 1kva. The APC does not cold start my system but the Powercom does. Both these UPS give me the exact same 28 minutes Backup time with a 19" CRT monitor and a sytem with 4 HDDs/2 Opticals/3x120mm fans and a USB scanner and Antec TPII 550w SMPS.