SMPS Power Detection

[anusoni]

Hi all been a long time since i posted, anyway wanted to know, how to determine if the 300WATT SMPS Frontech i have is actually a 300WATT SMPS or some lesser cheaper variant !
Also Anybody from chandigarh can guide me to a place here where i can buy good BRAND SMPS's ! ?
Also the ampere ratings written on the side of an SMPS, Do they mean anything ? how much minimum should they be for a regular system with 400Watt SMPS ?

 

[AlienTech]

Amps = Watts/Volts.
So 400 watts would be 400W/240V = 1.66 Amps. This only means the input usually. The output would be like 60-80% of this figure. Usually 250 watts would mean it needs a 240V supply at 1Amps. Providing like 20Amps 5V and 4Amps 12V. (100 watts + 48watts) with 50 watts going for the -12V, 3.3V and others.