We’ve recently done a few tests with the great little TPLink Tapo 110 smart plug. This has a energy use function and can tell you what power your device uses, as well as switching it on/off timed power etc.

PC energy usage is a hidden cost which can cause worry. While energy is never lost (basic physics) the energy PCs use ends up as low level heat, sound or light (from the screen and LEDs). This form of energy is not that useful so effectively can be regarded as an energy loss (especially in the summer when cooling might be an issue in a room).

We’ve tested some new and old PCs here are some examples:

Modern Lenovo M75s business PC, AMD Ryzen 5, 6 core machine, with NVMe SSD and 16GB RAM

Startup energy surge (seconds) 85W, Normal operation 7-10W, Running benchmark (perf test 7.0) 40W

So general running cost (electricity 40p/hr) at 10W = 0.01kW/hr= 0.4pence/hr,

8hrs=3.2 pence,

232 days (5 day working year 28 days holidays)=£7.42 a year.

9 year old i5 machine with i5 3300 processor 4 core, 8GB RAM, 240GB SSD, 8400GS graphics card

startup- 74-80W, normal use 38-58W, performance test 80-92W.

So general running cost (electricity 40p/hr) at 40W = 0.04kW/hr= 1.6 pence/hr,

8hrs=12.8 pence,

232 days (5 day working year 28 days holidays)=£29.70 a year.

Gaming PC with modern high end RTX 4080

Startup 100-200W, 158W-245W early use, 109-142W basic use, 255-308W on CS Go benchmark.

So general running cost (electricity 40p/hr) at 120W = 0.12kW/hr= 4.8 pence/hr,

8hrs=38.4 pence,

232 days (5 day working year 28 days holidays)=£89.09 a year.

As this is a gaming PC you probably are not using it like that. Here’s a example of another calculation

When Gaming at 280W cost= 0.28kW/hr= 11.2pence/hr

5 days gaming at 3hrs (adjust this truthfully now)=£1.68 week = £87.36 year

My gaming PC, 9400F, GTX 1070, 32GB

Real usage figure for Feb 2023 30.8kWh =£12.32 a month

Variability and disclaimer

Please don’t take these figures as scientifically significant, there’s a ton of variable and we are using a pretty basic measuring device (the Tapo). But as a general rule it gives you an idea of cost of running the machines. Its certainly worth shutting down machines at night, we measure 0.1W to 0.2W on standby even for gaming systems.

Discussion about power saving modes and wear and tear.

Shutting machines down used to cause undue stress on power supplies (when they had hard switches), however leaving supplies providing power (with a machine running) is probably going to wear a supply out as well, as might switching it on and off physically . Having memory energised (like in sleep mode) powers the whole board. I don’t know how this affects lifetime of PC components, but we know some PCs used daily can last 10 years with only devices like fans and spinning hard drives wearing out.