How can I tell how many watts my computer uses at idle?

I have an HP Pavilion Desktop PC TP01-2000i with the i5-11400, and which I upgraded to 32GB of RAM and added an Nvidia Quadro M2000. I leave it on all day because I run a Plex server for my HDHomeRun and my movies. I also added the graphics card because I needed it at the worst time to buy a graphics card and this was the only one I could find for a slightly decent price, and I like to play BeamNG.Drive. Plus I edit a few videos and photos and like to play around with VMs so I added RAM to max out the admittedly overkill 32GB.

I’m trying to save money on the electric bill each month (especially since I’m not using the thing all that often between work and everything else, so I don’t NEED the graphics card and 32GB of RAM), and I’m wondering how many watts this thing is using with the monitor off and a few external USB HDDs plugged in. I’ve turned the Windows power settings down to “most efficient” or whatever Windows 11 calls it, but changed the setting to never sleep. Before, I had an M1 Mac Mini that I sold as I needed Windows for work, plus I was a bit paranoid about all the components being soldered together especially storage, but I loved the idea of the computer using like 2 watts of power on idle. Am I anywhere near that mark with the power settings turned down or should I just be looking into something like a NUC or similar if I want that kind of idle power consumption?

You can either put all the specs into a site like Power Supply Calculator - PSU Calculator | OuterVision (although prob won’t answer your question about the consumption when idling) or get a cheap plug in energy monitor, which is a handy thing to have around anyway.


Yeah I’m think that monitor will be best for getting a solid confirmation. I’ve tried those calculators and downloaded Open Hardware (can’t remember the last word, I’m not at my computer at the moment), and like you said the calculator doesn’t show idle consumption, and the program would only show the graphics card consumption (which claims 20 watts on that alone so I’m thinking this is using more than I’d prefer). That same program shows me my laptop uses like 2 watts on idle so I think that gives me my answer. I’ve seen graphs online comparing the i5-11400 to other systems and they claim the idle is around 70 watts and I couldn’t tell if that was accurate or not, but now I’m thinking that’s gotta be close to what I’m experiencing. Thank you!

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I now leave my Plex library offline, rather than have it available 24/7. If I do want to watch something it’s no big deal to boot the PC and mount the drive. Interesting how my attitudes are changing wrt. energy consumption.

But yes, there must be a more efficient way of hosting your library, although involves buying new kit of course.

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Yeah I used to do that, but since I got the HDHomeRun, I liked the idea of leaving it on all the time for the DVR so I don’t have to think about when a show is recording. I’m thinking a USSF or NUC is just the better option (outside of a NAS of course, which I haven’t considered only because I used to work in electronics at Target and have accumulated a lot of clearance crap including external HDDs).

The killawatt may. I don’t know of any Windows, Mac, Unix or Linux app that will tell you that kind of information.

There is a program called Open Hardware [I can’t remember the third word in the name] that on my laptop will show the watts the processor is using, and that same program won’t work on my desktop. It only shows the graphics card’s. Still, I’m sure it’s not 100% accurate, so I’m just going to have to pick up a Killawatt and find out.

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I have one I bought ages ago from Canadian Tire that I was looking to see if it still exists. It looks like one called the EM100, which is still sold in Canada on Amazon, but doesn’t appear listed in US Amazon. So I took some of the same keywords, and searched. There appear to be lots of low cost options in Amazon, and probably you could find something similar locally at a hardware store.

It won’t be accurate, it can only tell you what the processor (and GPU) says they are using. It can’t take into account what the other chips and the motherboard itself is using. Even BIOS settings can greatly affect the amount of power the board uses, such as slower memory timing, turning off unwanted devices (or the other way round).

c’t in Germany does regular “best” builds and shows the best BIOS settings for their builds that reduce power consumption. Generally, the builds use around 30W in standard trim (manufacturer settings). enabling the correct BIOS options, they usually get it down to under 10W (Core i3 desktop processor at idle).

But you can only really use a hardware device that sits between the socket and the PC.

No, with optimal settings, you can get the idle of an Intel Core i3 on a very good motherboard down to around 10W, but as I say above, that is often many times that, if you use the manufacturers default settings, and using the on-chip graphics of the CPU, the GPU will at least double that, if not more.

It is one of the reasons I went from a Ryzen 1700 with nVidia GTX1060ti to an M1 Mac mini at the end of last year - electricity prices went from 25c/KWh to just under 40c, so saving on electricity is a priority.

I’d go with @PHolder 's advice and get a dedicated meauring device.

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I loved using the mini, but around the time I sold it, it was when that article came out about (I believe) the memory swap going crazy with reading and writing more than it needs to on the storage, and it scared me that should that kill my storage, I’d have a very expensive paperweight. I know that Apple most likely has high end hardware inside and the storage can most likely withstand a lot of reads and writes, but the non-repair friendly nature of Apple as a whole made me a bit paranoid unfortunately.