Where can I find out how much power "Computer Part of the Day" uses? It's easy to do a search and find out that a system built with the part du jour uses X watts under load and Y watts when idle but I can't find resources that list the power consumption for individual parts.

To add to the confusion, I found a table at Tom's Hardware that purports to list the power used for each part (CPU, motherboard, RAM, HDD, SSD, etc.) but they don't say where they got their numbers.


For the Intel i5-370k, Intel says that the TDP is 77 watts. I find a review that says a system built with the CPU uses 67 watts at idle and over 90 watts when under load.

I'm particularly searching for information to build a new PC so I need figures for the CPU, motherboard, RAM, HDD, optical disk drive, fan(s), graphics card, and maybe even SSD.

  • Just out of curiocity are you building for pure power efficiency for its own sake, or for cool running? – Journeyman Geek Jun 29 '12 at 23:20
  • Priorities (most important to least): Computer turns on, computer stays on (reliability), low noise, and then low temperature. – Zian Choy Jun 30 '12 at 0:21

This might help. TDP stands for Thermal Design Power. It says absolutely nothing about actual power consumption. TDP is a number to help you understand what something might require under normal/typical use - not during peak use. So if you're trying to calculate overall maximum power then only look at each component's maximum ratings. Don't concern yourself with things like TDP.


Well, as i understand it, the 'standard' way to measure power usage for components is to start with a standard test bed, swap out said component, and measure power under various conditions at the socket - tom's hardware has done it here.

That said, in most cases, power use is relative rather than absolute. You could have the same chip and have power usage varied by power supply unit construction and rating (Balance having enough power with having a load as close to the rated value as possible for best efficiency), motherboard (they may have different voltage regulator configurations) and so on.

In short, your milage may vary, with respect to real world power use, both compared to the ideal, theoratical TDP in the specs, and the measurements made by hardware websites.


I've found the eXtreme Power Supply Calculator works pretty well for calculating PSU requirements for a PC build. You could do the extra research on individual parts they might not list, but they seem to do well for rough estimates. I tend to focus most of my attention on graphics cards' total power draw at 'max throttle' since they can easily take 300-400 watts on their own. I also look at how much a PSU pumps out on the +12 volt rail(s).

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.