How To Determine Your Power Requirements
A Matter Of Simple Addition
While there are many online calculators meant to help you figure out how much power your build will use, they all estimate its maximum requirement. They then take into account the PSU’s peak efficiency at a load of 50 to 55 percent and make a (generous) projection based on those numbers. The drawback is that this method does not consider consumption when the computer is idle, which we already determined is where efficiency often appears worst.
The following table is meant as a guideline, showing you how much power a certain component is likely to use under a specific load. If you know the exact figures for your components, plug them in instead and do the math.
|Component Type||Description||Idle (W)||Load (W)||Number Installed|
|CPU||Current dual-core CPUCurrent dual-core CPU, overclockedCurrent quad-core CPU (Mid-range)Current quad-core CPU (High-end)Current quad-core CPU, overclocked (High-end)Older dual-core CPU (AMD)Older dual-core CPU (Intel)Older single-core CPU||2025354045355535||65909512514090-125125-14060-90||1|
|Motherboard||Current microATX board without graphicsCurrent microATX board with graphicsNormal mid-range board without graphicsNormal mid-range board with graphicsHigh-end boardHigh-end board, overclocked||153020253540||254035504555||1|
|RAM||Current DDR2 or DDR3 RAM, per 2GB moduleCurrent DDR2 or DDR3 RAM, per 4GB moduleOverclocked RAM per module (estimated)||234||456||1-4|
|HDD||Conventional hard drive||2||8-10||Varies|
|SSD||Current solid-state drives||1||4||Varies|
|ODD||DVD-ROM onlyDVD burnerBlu-ray reader/burner||112||61012||1|
|Fan||Normal CPU fan, mandatorySilent case fanPerformance case fan||123||1-323||1VariesVaries|
|Add-In Card||External sound cardTV cardController card||211||82-52||0-10-1Varies|
|Graphics Cards||Current office-oriented cardCurrent mid-range gaming cardCurrent high-end gaming card||10-1616-3025-35||35-7575-180180-375||11-41-4|
|Other||Cold cathode lighting, modding parts, etc.||See manufacturer info||Varies|
Now that we have an idea of how much power each component draws, calculating the overall consumption at idle and under load is easier. Based on this information, we will define a power window in the next chapter and choose the best PSU for the job.