Topic: Low Power Consumption PC

[west_london_red]

So along with everyone else I am seeing my energy bills each month and having a minor heart attack. So, thinking about things I can do to save some money (and the environment of course) and need to look at my PC.

The current PC I use for work is a gaming PC I built a couple of years ago, very high spec for the time (Intel 9600k CPU slightly over clocked, 1080TI GPU, 32GB RAM, 650W PSU) but work wise I’m only logging in and working in a Citrix session and will have iPlayer on in the background so the PC is working far within its limits but still probably using more power then need be so am considering buying one of those £200 micro PCs about the size of a mobile phone with 8GB of RAM, Intel Atom or Celeron that should be enough for a Citrix session over 2 monitors and listen to the radio or iPlayer outside of the Citrix session and use a fraction of the power.

Anyone have any experience of those machines or anything I might be missing?

[Kashinoda]

It could take you years to save on energy bills and end up with a machine with little resale value, you're likely to be best off just getting an 80 Plus Gold PSU (if you haven't already got one).

Lets say you have a 600W power supply for your setup and you put Windows into 'Power Saver' mode, you'll likely stay well within 20% of the PSU's capacity (this is the minimum the PSU can run at).



Going by the table above you have 88% efficiency at 20%, so 20% of a 600W PSU is 120W which at 88% efficency equates to 136W (120 / 0.88).

The average price for energy in the UK is 17.6p per kWh, so running such a PC in 'Power Saving' mode will cost £69.94 per year at 8 hours a day:
https://www.omnicalculator.com/everyday-life/electricity-cost

For a mini PC you could get something like this:
https://www.scan.co.uk/products/asus-barebone-mini-pc-90mr00ia-m00550-intel-n4505-ddr4-usb-32-gen1-type-c-ac-wifi-25-gbe-m2-pcie-25

Once you've added a SSD and RAM it may come to £250-80 depending on what you want, the MAX TDP is 10W

Using the same calculator above it will cost you £5.14 a year to run at 10W, saving you £64.80 a year. After 4 years of use you'll start to see a return on investment or maybe a little sooner if you're using a Bronze/Silver PSU in your main PC.

Obviously I've made a ton of assumptions if you want a simple answer just grab one of the ASUS Mini PCs - I got one for my uncle:
https://www.scan.co.uk/shop/computer-hardware/home-office-pcs/mini-pcs-integrated-cpu-fully-built

[west_london_red]

First of all thanks for the detailed response.

I’ve checked the PSU and it’s bronze rated. I have considered using the Windows power settings but what I don’t want to do is start faffing around with power settings whenever I do feel like a bit of gaming.

Other factor worth considering is that the kWh cost goes to 28p from 1st April, and by October when they review the prices again 40p is a realistic expectation.

What I was looking at is this or something similar that I can buy for £180:

https://www.amazon.co.uk/NiPoGi-Processor-Computer-Ethernet-Bluetooth/dp/B099ZF5WZW/ref=sr_1_10?crid=2W2P7809C3XVL&keywords=micro+pc&nav_sdd=aps&qid=1647292106&refinements=p_n_feature_browse-bin%3A1481781031&rnid=182781031&s=computers&sprefix=micro+pc&sr=1-10

That has a 30w PSU

[Red Raw]

If you are used to a relatively high performance PC you may find a mini PC slow and frustrating to use. Passive cooling and tiny cases also means that they can get very hot under load. We used to have one in the office that you could fry an egg on!

I agree with Kashinoda on the PSU.  I always go for gold (minimum) because as well as energy saving the internals are generally higher quality, meaning more stable power delivery and less chance of frying other components. It is worth noting that the power curve for most PSUs will show peak efficiency at around 50% of capacity with a consdierable drop off below 25% (which is why a massively oversized PSU is not a great idea).

If you want to see what your PC is really using I would be inclined to pick up a plug-in energy meter (about £20), see what the load is for different tasks. Then you will be in a position to fiddle with some of the settings to see whether it is worthwhile. Windows energy profiles are easy to set up and switch between. Your graphics card too should have some active energy management options in the settings and if your motherboard has an option to save OC profiles you could also try underclocking the 9600k for work tasks.

If you are looking to save electricity however you will may find that the PC is only a fraction of your annual consumption and there are better things to do to save energy - switching stuff off, not overfilling the kettle, putting lids on pans when cooking etc. Heating a 180 litre immersion heater once a day for instance will cost in the region of £1000 a year at 28p/kWh.

If you are happy fiddling with technology (as a PC builder I guess you are) you could even have a go at monitoring your electricity consumption. This is generally the first step when looking for effective energy saving strategies. If you are interested I can post some info on affordable high resolution energy monitoring at home which will show you exactly where you are using energy.

[west_london_red]

So I ordered the Micro PC and it’s absolutely fine speed wise for work purposes, as I log in via a Citrix session all the actual work is being done in the server session and all I’m doing in effect is streaming a desktop. It does have a fan that kicks in if it’s under a high enough load but that hardly ever kicks in while I’m just working although things like kicking off a Windows update can cause the fan to kick in for a while.

With regards to the gaming PC, yeah I’m reasonably comfortable in fiddling with the settings, what I don’t want to do is regularly changing them depending on whether I’m working or occasionally gaming because sooner or later I’ll get lazy and stop changing them. I tend to mess about with the settings when I either build or upgrade and find a bit more performance and once I have found something stable I’ll just leave it there, I’m not an extreme overclocker or anything close to that.

Keep in mind though the micro pc has 30w power cable, and no matter what I do to the gaming PC it’s always going to use several times more power then that. Will it save me money against the initial outlay, probably not, but I might also retire the gaming PC as I don’t get much time for gaming and I’m not spending £700+ on a current GPU either, and if I do retire it that’s a decent amount of space I save too with the Micro PC compared to the tower case.

Please share the monitoring you mentioned, unfortunately my family are really poor with energy use. My parents live with me so there’s 6 of us in the house and there’s always a lot going on in multiple rooms, then you have Mrs WLR for who the heating isn’t on unless it’s at 23c and I’m having to constantly nag her to turn the damn temperature down to even 21c as a compromise, and the old owners of the house left behind a semi industrial 4.6kwh dryer that my Mrs insists on using when it’s only half full that sends our bills through the roof.

[Red Raw]

...
Please share the monitoring you mentioned
...

OK - you asked for it! 

Commercial datalogging kit can get very expensive and historical smart meter data is not always easy to get hold of and, at half hour resolution, is not particularly helpful when it comes to disaggregating loads. There are some homebrew options such as those at https://openenergymonitor.org/ which use Aruino/Raspberry Pi as a basis to build a logging system from the bottom up.

In practical terms a standalone logger is often the easiest way to grab some data for diagnostics. These millivolt loggers are getting hard to find now but are a (relatively) low cost solution for getting high resolution data: https://cpc.farnell.com/lascar/el-usb-act/data-logger-w-current-clamp-input/dp/IN07964

The logger plugs into a split core current transformer with a millivolt output (something like this https://uk.rs-online.com/web/p/current-transformers/9145294) which clips round the line or neutral on your consumer unit. This is non-invasive and does not involve cutting into live wires but obviously if there is any doubt you should consult an electrician.

This logger will record 127,000 time stamped data points, so at a resolution of one reading per minute (say) it will log for up to 88 days, although you can stop/download/restart when ever you want. The two AA batteries will last about four months at this resolution. The logger connects to the PC via USB to set parameters and to download the data when you are done. The logger software is free and reasonably simple to use on a Windows PC.

The output is current in amps which is all you need to see the consumption patterns but you can convert to power by multiplying by the fixed voltage at your home (~230 V). If you multiply the power in kW by the duration of the logger time step in hours (1/60 at a one minute resolution) you get energy in kWh (on your bill one 'unit'= 1 kWh). Note that strictly speaking this will give you 'apparent power' (in kVA) so might not agree completely with your meter which measures 'real power'. This is not the place to go into AC power theory but there is a beer analogy here which explains it loosely: https://www.fluke.com/en-us/learn/blog/power-quality/power-factor-formula

If you plot the current/energy data in a spreadsheet as a simple line chart the consumption pattern will give you a good idea of what is using the power. Fridges and freezers for example have a distinct on/off cycle which usually shows itself overnight. You can make a note of when you run dishwashers, washing machines or other appliances and you will soon recognise their signature in the chart. As well as the peak loads (when things switch on) it can be very useful to see what your baseload is - this is the stuff that is on all the time and will show as a consistent low load across the monitoring period. Because the baseload it there 24/7 it can comprise a large portion of your electricity consumption.

If this sounds complicated it is because it is, but once you have your head round it the results are often fascinating.