Intended for powering 24V AC CCTV camer... Dantech DA449 1 x 4 Amp, 24 V DC or 1 x 8 Amp 12V DC power supply unit DA449 will provide 8 Amp 12V DC (13.7) or 4 Amp 24V DC (27.4). This variant also ...

TDSi 2921-0281 is a boxed 2 A power supply unit with back-up battery charging facility and... TDSi 2921-0282 boxed 3 A power supply unit TDSi 2921-0282 is a boxed 3 A power supply unit with back-up ...

Agreed if it was a modern ATX unit, that probably wouldn't be an issue. AT or ATX will work fine, however I would strongly urge you to use a proper CCTV power supply. I have used at least a dozen ...