How can one tell if the PC power supply is 350W or Whatever W is for real ?

Question

Some people tell me that sometimes what is written on the power supply box is not real ... like a power supply stating that it's 450W but in fact it's 350W or 300W ... and what's the meaning by "a motherboard needs at least a power supply with 350W and 12V/18A" ??? how can i know if it's really 12 Volts and 18 Amperes at least ??? and where is that data located on the power supply ? cause there is so many data like the +12V , -12V , +5V , -5V , 3.3V and what does those represent ? i know it's so many questions in one .. but i badly need the right information cuz i'm up to buy a new PC ... Thanks !!!

Answer 1

Sorry, but I am not sure why you are concerned . . . if you are about to buy a new computer. Whatever size PSU comes with the computer should work fine as long as you don't add more equipment. Some computers come with only a 145W PSU and work fine, since they are sized for the origninal equipment. Adding more hardware might require a bigger PSU, but you can deal with that when you add something.

As for your orignial question: I've never doubted the size of the PSU that is advertised on the unit. As long as it runs my computer, I don't wonder (or worry) about its true size.

Answer 2

All the test of PSUs by Anandtech, and by, Tom's hardware support the truth that the world is being cheated with PSUs that are about half the power of the advertised rating on the label!

The voltages are critical for the delicate components. but, when the current is exceeded, the voltage will drop drastically!

Each of those voltages you listed is needed for different components, drives, accessories in the computer!

Now, in the purchase of a new computer, the system does meet the needs of the system being sold, and had probably been tested.

If you install a new drive or two, then, you would probably install an extra fan to the rear of the case. The power might be exceeded now, with the three accessories, no matter what a pimply faced sales man would declare, just to get your sale!

Please, also, check out google.com for 'Power Supply'

Answer 3

Power supplies, like anything else, follow the age old adage "you get what you pay for". Power supplies (PSUs) are rated at a given output at a given ambient temperature. Cheap single fan budget psus likely couldn't hit their rated output if cooled with liquid nitrogen. Features to seek in a psu would be active PFC (power factor correction), multiple 12v rail output, PCI Express support, and SATA support (of course thats if you intend to upgrade at all in the future and keep the same PSU). How much you spend is really up to you, but personally, I don't even start looking at power supplies until they're in the $100 and up range. Why? Because the problems from an inadequate power supply are the HARDEST to troubleshoot as they happen the most randomly, and can appear to give similar symptoms as bad memory, overheating, and virus problems. The power supply is by far one the MOST important and MOST overlooked choice in your list of components.