The Power supply is one of the most important component in a PC. It powers up the whole system and without a PSU a PC is incomplete. There have been many discussions over the years regarding which power supply to use in a system. People have a wrong perception of spending less on a power supply and more on other components. This can prove fatal for your system and this is what we will discuss in this post.
The decision of buying a power supply depends on three major things:
- Power output
Power output is the first thing to look at before purchasing a PSU. An average system requires not more than 300W at full load but it is not recommended to buy a PSU that barely fulfills your power requirement. Power supplies operate within some perimeters and these should be taken in to account before making your decision.
The first perimeter is the headroom. If your system consumes 300W power then a minimum 500W or 600W power supply is the right choice. Reason being, if you purchase a 350W PSU then it will constantly run at 90% load, as a result it will produce more heat and decrease its lifetime. Also if you upgrade your PC in the future then you will have to spend extra money to upgrade your power supply as well. So in the end you will spend more money on your system compared to what you could have saved if you bought a sufficient power supply.
There are dozens of power calculators available online. These calculators are designed by PSU manufacturers and will give you a fair idea of which power supply to go for. Second thing to look for in the power category is the power given to each rail. Rails are different voltages which are supplied to different components in your system. The most important thing you should look at in the specifications of a PSU is the +12V rail. This rail provides power to your graphics card which is one of the most expensive components in high-end PCs.
There are two types of 12V rails, single and multi. A PSU with single +12v rail is the best option because the GPU will receive uninterrupted power which might not be the case in a multi-rail PSU. In a multi-rail PSU, each rail has a max output limit so you have to be careful which component is plugged in to which rail. For example, if you GPU requires 25 amps then you should use the rail which supplies at least 25 amps otherwise it will trigger Over-power Protection and shutdown. In terms of performance both PSUs are good and safe but single rail PSUs are still preferred over multi-rails one.
Higher wattage power supply does not mean that it will consume more power. It just gives more headroom for future proofing and efficient operation. If your system components consume 500 watts then both a 500W and a 1000W PSU will consume the same amount of electricity. A power supply with more protections is a safe bet because in case of any unforeseen circumstances it will protect your components.
Moving on to efficiency, higher efficiency power supplies have a better build quality. So an 80+ power supply unit will use better soldering, capacitors, MOSFETS and other components. It will also produce less heat and perform at low noise levels. 80+ certification means that a power supply will provide 80% of its rated Total Design Power (TDP) to system components while the remaining 20% is wasted as heat (depends on the efficiency rating).
The higher the rating the better the power supply.
Refer to the 80+ efficiency table below for reference:
As you can see in the table above, at 50% load power supplies have the highest efficiency. This is the reason you should get a power supply with double TDP rating compared to your system requirement. This will keep your system cooler and produce less noise. Higher efficiency rated power supplies are expensive so an 80+ Silver or 80+ Gold should be your priority.
Lastly, brand is extremely popular when it comes to power supplies. There are 100s of power supply manufacturers but not all of them produce quality units. You should always buy a power supply from a reliable brand because they use quality components that deliver stable power and have a lower fail rate. Never cheap out on a PSU by buying an unreliable brand or a Chinese unit because you will risk damaging your system. Corsair, Be Quiet!, Thermaltake, Cooler Master, Seasonic, EVGA and Xigmatek are reliable brands. Seasonic and Corsair lead the pack with the best PSU units and quality components but they do come with a higher price. The higher price is justified for saving your $800 investment.
So if your system consumers 500W then you should buy a 1000W 80+ Gold power supply. This unit will set you back $150-200. Other factors to look for are cables and connectors. Latest power supplies feature modular cables which is a very nice addition. Modular cables make less mess inside your chassis which allows better air flow. Secondly, you can use only those cables which are needed and avoid a wire clutter. Secondly, new technologies such as Corsair Link allow you to check your PSU’s internal readings with the help of a software. This way you can monitor your PSU as well as your system.