Which PSU? Power Supplies and 80 Plus Ratings Explained
Power supplies are rarely the first component on your mind when researching parts for your next rig, however few will disagree that getting your choice of power supply right is an essential step in the process. For most of us that usually means 'how many Watts do I need' rather than 'how efficient is this PSU at 50% load', but as power demand creep ever higher, the importance of an efficient PSU increases with it.
The basics of Power Supplies
It should come as no surprise that the purpose of a Power Supply in your PC is to (you guessed it) supply the power, or more precisely to safely and efficiently convert and regulate power from your mains socket to your components - which have different power requirements.
Some common questions of shopping for a power supply that we'll answer below are:
- Is the power supply compatible with your case?
- Is the power supply compatible with your graphics card?
- How many Watts does the power supply need to provide?
- What does the 80 Plus Rating mean?
- Do I need a modular power supply?
Power supply sizes and case compatibility
With the vast majority of PC cases you'll be using an ATX power supply. This is the most common standard and absolutely the correct type of PSU to install in most cases. The exception to this is when you're looking for a particularly compact, or small form factor PC build - in which case things get a little more complicated and you may need a smaller form factor power supply, such as SFX. Your best bet is to check the specifications of the case you want to use as this should tell you the compatible power supply form factors.
Power supply compatibility with graphics cards
Power supply manufacturers supply an array of different cable configurations to ensure you'll have what you need to get your system powered up, so most of the work here is done for you, but it's prudent to check the requirements of your graphics card to make sure it's correctly catered for.
At CCL you can find this information under the specifications tab on any graphics card product page - the example below shows 2 8-pin PCIe connectors are required - you may find many PSUs provide this PCIe connector described as a "6+2 pin PCIe" - that just means the pins are grouped into a section of 6, and a section of 2 - so these are still 8-pin connectors and would be fine to use.
How many Watts does my Power Supply need?
The main consideration for powering a gaming PC is supporting your all conquering graphics card - GPUs are the biggest power drain on your system and it's always sensible to aim above your requirements as a higher wattage doesn't necessarily mean it'll always be drawing that much power - rather that it has the ability to if it needs it.
Power requirements also tend to creep up with each release of more powerful processors and graphics cards, so if you're planning a PC build you can upgrade in future, you'll need to consider this, and again aim above your immediate needs to prevent having to replace the PSU in order to support another upgrade down the line.
It's not possible to make a PSU recommendation without knowing the details of the system you're building, part by part, but as above, recommendations for any graphics card can be found on the product page under specifications - this is a good way to select a PSU safely without getting into the nitty gritty of exactly how much power each component in your system is using.
What is an 80 Plus Rating and does it matter?
The ratings you'll see on every power supply should absolutely be a factor in your decision making, as this determines the efficiency of the PSU - a more efficient power supply will use less energy, and lose less energy to heat - decreasing the cooling workload of your system, and wear and tear on the PSU.
The 80 Plus rating tells us that a maximum of 20% of power is lost as heat, and the Bronze, Silver, Gold, Platinum and Titanium ratings narrow it down further from there. Most PSUs these days are 80 Plus rated, so it's something you should expect to see on any good quality power supply unit.
For most gaming PCs you're looking in the Bronze to Gold bracket, depending on your budget - PSUs at the Titanium end of the scale are a pricey proposition and that level of efficiency isn't necessarily required for your everyday gaming PC.
The table below breaks down the efficiency of each 80 PLUS rating against the rated power load. The difference doesn't look like much, but if your PC is in use for hours at a time, 365 days a year, this adds up and over time you might see a saving you made on a lower cost PSU gradually wiped out by the increased energy cost of running your PC.
Do I need a modular power supply?
A modular power supply comes without the cables built-in to the power supply - that means you only have the cables you actually need inside your case. If you want to maximise your airflow and cable management, this might be a consideration, but otherwise it's not a necessity. For a happy medium you can opt for a semi-modular power supply, which is exactly what it sounds like - some cables are built-in to the supply and others have modular connections.
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