Notebooks Is there an easy way to guess at laptop power use?

Hi all,

For some complicated reasons I'm in need of a laptop that I can leave on all the time. I already have both a Raspberry pi 4 and a Wyse 3040 as always-on machines, so I'm very used to using fewer than 5W and I would like to keep it as low as possible given the fact that British Gas have once again posted record profits.

The screen and wifi will be off most of the time (but will occasionally be needed), so I'm talking just the 'normal computer bits' here.

I'm scouring ebay for the cheapest possible old machines, but obviously the newer (and more expensive to buy) hardware probably has lower power consumption.

Is there an easy or quick way to make an educated guess at how much power a laptop will draw from the wall at idle? Up until now I have been looking up the chipset, can I improve on that?


Thanks in advance.

 

If your PSU supports it hwinfo should show it.

Otherwise you can run something to max out your CPU and GPU and see what they hit - adding those will give you a basic ballpark.

https://www.hwinfo.com/

 

Oops my bad.

I blame my poorly cat - I'm also talking gibberish as well as posting it.

E: Although it does report minimum values too. That's it, I'm stopping thinking now, my brain is so fuzzy at the moment I can't rely on anything being a good idea

 

You might be able to look up the specs on the power brick. 45W is pretty typical for DC output on bog standard 15" laptops in the past 10 years and laptop power bricks are generally more efficient, as they are low power and specific to the machine. With the screen off, sub 10W at idle probably isn't out of the question.

Wikipedia also lists the TDP of the processors, which is probably your best bet to know how much power a laptop will use.
https://en.wikipedia.org/wiki/List_of_Intel_Core_i5_processors#Mobile_processors

If the box is going to be headless anyways and you want a bit more powerful of a CPU, mini/micro workstations based on v2 and v3 Xeon-E3 processors. My parents have some old HP Z220's I got off ebay for a $50 each from a local electronics recycler and they idle at 17-23W.


Edit: I just tested my laptop, which is more modern with a 4800H cpu and it idled around 11W with the screen on and 6W with it off. The power factor at such a low load was around 55%, but I assume you aren't billed by apparent power.

 

Thanks all. Looks like I was thinking along the right lines.

 

Maybe something like a Windows 10 tablet?

 

Not sure what your target is but I use a compute stick with 14" touch screen and it's <5w total, runs off a low power micro usb supply. The screen itself is using 3.2w if I run high brightness watching a movie but can be less on low, so with that off idling the compute stick is next to nothing ~2w, runs windows 10, if fully loaded it might nudge 10w.

For a laptop I also still have and use a Coda Spirit 13 inch which was <£100 new and is similar hardware to a compute stick in a laptop, so is similarly low power, not measured it though.

 

I might be being thick, but the simplest way, would be to use one of those wall plug meters?
If I've got the OP wrong, my bad - half asleep!

 

Unfortunately I might make a mockery of ebay's returns policies if I had to buy them in order to test them first. ;-)

 

As long as it's one of those awful sellers that message you with broken English at 4am from another country making out that it's posted from the UK and will be with you in 2-5 days despite coming from abroad and taking a month, then do it, you'll get to probably keep it too haha!