If They Have The Same Wattage, They Have The Same Performance!

Some people say, if it looks like a duck and walks like a duck, it must be a duck. However, even if they are right, no two ducks are the same. You have some fat ducks, some thin ducks, with others in between. If you are in the market for a duck, surely you are not going to randomly pick your duck, right?

The same applies to power supplies. They may look the same and work the same way, but they are not necessarily the same, even if they have the same rated wattage. Just like you want a fatter duck for your dinner, you want a better power supply for your system.

When people talk about power supplies, they might boast of the cheap 500W PSU they picked up last week at the store for only $50. And yet, the same store sells another 500W PSU for $200! Now, that must have been an insanely great deal you missed back there.... NOT!

Seriously, we, the buyer, should always be wary. If something's too good to be true, it's often too good to be true. Most of these "500 Watt" power supplies can't even generate 300 watts to save their lives.

You might be wondering how can these manufacturers get away with false advertising. Well, it isn't really false advertising, because those power supplies can generate 500 watts, just NOT under normal conditions or in the voltages that you need. So, let's take a look at how bad power supply manufacturers go about their deception...

Power supplies are just like most electronics. They function better in some environments than others. If we use an analogy of a 100 meter sprint, power supplies would naturally prefer to do it in the electrical equivalent of a well-maintained track, as opposed to a dirt track. Unfortunately, dirt tracks are cheaper than well-maintained sprint tracks and the same applies to power supplies.

Power supply manufacturers who want to cut corners can design their 500W power supplies to do that only at lower ambient temperatures, instead of the normal industrial standard of 50°C. They also put artificially high loads on voltage rails that are obviously not going to be used that much, just to boost the overall wattage without actually improving its capacity to provide useful power.

For example, a power supply that delivers 100W on the 3.3V rail, 200W on the 5.0V rail and 300W on the 12V rail is technically rated for a power output of 600 watts. You might ask, what's so bad about it? Well, modern PCs for one thing, favour the use of the 12V rail.

The processor, motherboard, chipset, graphics card, all run off the 12V rail. So, it's obviously better to have the power supply deliver most of the power through the 12V rail, instead of the other two rails. Even though this 600W power supply may be really cheap to buy, running a heavily-loaded system with just 300W on the 12V rail will kill your PC components real quick.

The easiest way to avoid this problem is to read the specifications on the power supply's box. They can mislead you, but they can't lie. Instead of just looking at the peak load rating, take a look at the specification that says ‘Max Sustained Load’. That tells you the kind of power the power supply can sustain continuously.

Then try adding up the wattage of all the rails. See if it all adds up. Also look for the temperature they tested the unit at. It should be written on the box or on the power supply itself. So, don't get misled into buying something that could cost you your whole PC. Buy smart and ask questions.