Picking the right PSU
Because the PSU does not contribute
directly to the performance on your system, all too many users decide to
purchase the cheapest supply they can get away with. This is not a sensible
policy, as an inadequate supply is far more likely to fail and will contribute
significantly to your system’s noise and power consumption. A common
misconception is that a more powerful PSU will use more energy. This is not the
case; if your system uses 300W it will only pull the power it actually requires
whether you use a 300W PSU or a 1,000W model.
Many cheaper power supplies do not provide
the levels of wattage they claim to. For this reason you should be very wary of
buying a power supply that is priced at a level too good to be true. It’s easy
to buy ‘850W’ PSUs from online retailers that cost less than $30, but these
supplies will certainly not be capable of delivering this kind of power output.
Modern PCs require that most of the power is capable of being delivered over
the 12V rail, the most powerful of the three voltages delivered by PC power
supplies. All too many manufacturers bump up their ratings by claiming the
majority of the power their supplies deliver is over the 3.3V or 5V rails. In
actually, the PSU’s ratings are simply fabricated.
An easy way to ensure that you get a PSU
with a realistic rating is to ensure you only buy models that are 80 Plus
certified. This means that you will be buying a product that has been
independently tested to ensure that it firstly is capable of its quoted output,
and secondly is at least 80% efficient, which will reduce your electricity
bills and heat output compared to cheaper entry-level units.
If you’re using a system that only uses
integrated video, then you do not need a hugely powerful PSU. Aim instead for a
modestly specified unit from a high-quality manufacturer like Corsair, Enermax
or OCZ. Each of these manufacturers offers good quality 400-500W PSUs with 80
Plus certification that often cost less than PSUs without certification citing
unrealistic wattages.
80 Plus PSU
If your system has a mid-ranged video card,
then you should aim to feed it a little more juice. Something in the 500-600W
range should be ideal, and once again you should stick to a reliable
manufacturer. Again, Corsair and Enermax have suitable models, but Thermaltake
also offers some competitively priced 80 Plus certified models that are worthy
of consideration.
High-end single GPU systems, or those with
hefty overclocks will need a 650-750W PSU. This is a popular wattage range and
there is a wide selection of products available. As usual you should always
look for the 80 Plus certification logo on your prospective purchase, and don’t
just take the manufacturer’s word for it that they have a certificate; you can
look them all up on the www.plugloadsolutions.com.
If you can’t find the PSU you want to buy, it probably isn’t actually 80 Plus
certified after all.
The only systems needing more than 750W are
those equipped with monstrously powerful dual GPU video cards or an unusual
number of drives. For these systems, premium 800-850W PSUs are available. A
good 850W PSU will cost you in excess of $150, with some 80 Plus Gold (>90%)
certified models from Enermax and Antec costing over $225 each!
There are, of course, even higher-rated
models on the market, some of which are capable of outputting 1,000-1,200W of power.
These are needed for so-called ‘dream PCs’ that combine three video cards in
SLI or CrossFire, or two dual-GPU cards for quad GPU support. If you have the
cash to splash over $1,500 on video cards alone, you probably won’t balk at the
$300-plus price of these immensely capable PSUs.
