Refine search for Peripherals

  Leave a comment      Email this to a friend TrustedReviews Newsletters

There are also voltage requirements that all power supplies are required to operate within, as if one of the power rails delivers too much or not enough power, the computer won’t work properly and can cause irreversible damage to your components. As such, the 12V rail is the one to keep an eye on. The 12V rail(s) have to operate in between 11.40V to 12.60V, the 5V rail between 4.75V and 5.25V and the 3.3V between 3.14V and 3.47V. It’s actually preferable to get too much rather than too little power, but it’s not good if a PSU delivers higher voltages than those stated in the ATX specifications. For more information about power supply guide lines please visit Formfactors.org.

Other things to consider before making a purchase are the power requirements of your PC. An average PC will usually not need more than a 300W PSU, but with the latest generation of graphics cards and CPUs more power is needed. There is no straightforward way of calculating exactly how many watts you should go for, as it all depends on what components you mix and match.

The latest Intel Pentium 4 processors can draw as much as 120W at full load. This only tends to be in short bursts, since unless you’re doing something very CPU intensive you never load your processor at 100 per cent. Of course if you’re a gamer and have a GeForce 6800 Ultra, you probably know that nVidia originally recommended that you use a 480W PSU. This is overkill, but the recommendation is based on the estimated needs for the rest of the system. The remaining parts in a PC draw fairly modest amounts of power, with hard drives tending to be the next most power hungry.

One final aspect to be taken into account is the length and type of cables that the PSU has. Some of the PSUs on test had wires that were simply too thin for the job they are expected to do, and these got excessively hot even at 75 per cent load, which is not a good sign. The wires used should follow the AWG standard and most power supplies use 18AWG wiring. However, some manufacturers use 20AWG to save money, which is not recommended, and these were the PSUs where the wiring got hot.

Overly long cables could cause airflow to be restricted, but cables that are too short would cause problems in large cases. Nor is it good to have too many Molex connectors on the same cable, at least not if all of the connectors are used. The reason for this is that you will lose power between the first and the last connector if there is a device attached to each of them. In turn this means that you might have problem operating your DVD writer, for example, as it won’t get enough power. Braided cables are always a bonus as they are tidier and often look much better than plain ones, which might be important to you if you have a case with a window.

We found that there were certain power supplies in this group test that wouldn’t deliver what they where rated at and this is a major problem. It’s not normally possible to know how close to its actual rating a given PSU will perform. Usually cheap PSU are not as good as more expensive ones, but this doesn’t always hold true. We have seen examples of 650W power supplies selling on US websites for $30, and to be honest these will never deliver 650W. There are of course some brands that have become synonymous with very expensive but reliable power supplies and Antec has to be the most famous one. Sadly Antec wasn’t able to supply us with a sample in time for our trip to Germany, but we are looking at doing another group test some time later this year and hope to include them.

For now, let’s move on to the power supplies we did get in and see how they performed and what you get for your money. It's worth having a look at the efficiency results, as if you know what you pay for your electricity you can calculate how much each of the power supplies would cost you to run. Please remember that a score of five is average and anything scoring below five is generally not a product we would recommend.

Add your comment