Summary
Yesterday (June 5th) was World Environment Day. In that spirit, please disconnect your AC Adapter once the battery is fully charged. It is good for the environment. Good for the pocket in the long run too. Let chatGPT tell us more.
Not convinced ? Read on to know why.
Background
I touched keyboard of my laptop this afternoon, and felt it was rather hot. It was mid-afternoon, outside temperature was in the low 30 Degree Celsius, thanks to a delayed monsoon here in Bengaluru. I had stepped outside for some work (dog walking !), and had left the laptop for charging. The laptop is a Lenovo Thinkpad Gen III with AMD Ryzen 5 5600U with upgraded disk and RAM. Specifications are added at the end of this post.
I use Linux Mint on this dual boot machine. When I ran the sensors command, I could see that the cpu and the disks were indeed running rather hot. This should not have been the case: the machine was practically idling.
After removing the AC adapter, and a few minutes later I ran the sensors command again. (4 minutes for the detailed oriented OCD folks). The CPU, GPU and NVMe disk temperatures had indeed dropped.
Why would that be? I asked myself, and thus began a journey of exploration.
Possible cause(s) for the laptop heating
I am not an authority on laptops and heating, but I do know that some of the factors that can cause heating can be:
— outside (ambient) temperature
— hardware intensive processes (gaming, large data transfer, bitcoin mining, AI Image generation…)
— battery life (older batteries run hotter)
— dust accumulation on fans
— thermal paste on CPU needs replacement
But since the laptop was in idling state, and this being less than 2 year old machine, most of the above did not apply. I would even go to the extent of saying none of the above parameters apply.
Caveat: The above list of reasons is not exhaustive, there may be other reasons.
chatGPT to the rescue
I asked chatGPT to format the two sets of data in a table. Then, I asked it to define each of the parameter that had changed in the ‘before and after’ scenario. Finally, I asked it to offer possible explanation for drop in the temperatures after removing the AC charger.
For the aspiring ‘prompt engineering’ enthusiasts, I have posted my exact query at the end of this post.
Before and After Temperatures, and what they mean
Here’s the formatted data, followed by an explanation of each parameter.
Explanation of Parameters:
fan1: The rotational speed of the laptop’s fan, measured in RPM (revolutions per minute).
CPU: The temperature of the laptop’s CPU (Central Processing Unit) in degrees Celsius. It indicates the heat generated by the CPU during operation.
vddgfx: The voltage supplied to the GPU (Graphics Processing Unit) of the laptop.
vddnb: The voltage supplied to the Northbridge component of the laptop’s motherboard.
edge: The temperature at the edge of the GPU.
Composite: The composite temperature, which represents the overall temperature reading for a specific component.
Sensor 1: Temperature reading from a specific sensor.
Tctl: The temperature of the laptop’s CPU, measured at the control temperature.
I have a second NVMe disk on this laptop, but it’s temperature was identical in both cases, at 25.9 Deg C. Therefore, I removed it from the above table and other considerations. It may be possible that the sensors command was showing faulty reading, but then the other readings might also have shown that error. Particularly in light of the below explanation by chatGPT, let us assume that is not the case.
Possible cause for temperature drop
The response from chatGPT was rather insightful.
The drop in CPU, GPU (amdgpu-pci-0500), and nvme-pci-0400 temperatures once the AC charger is removed can be attributed to reduced power consumption.
When the laptop is running on battery power, the system may adjust its performance to conserve energy, resulting in lower CPU and GPU utilization. Additionally, the cooling system of the laptop may operate differently when not connected to the AC adapter, leading to slightly lower temperatures.
What this really means:
This post may seem obvious to some, or “so what?” to others. But a small test with laptop temperature sensors provided some interesting explanation on why we should remove AC charger once battery is fully charged. The main reason: Thermal performance.
Thank you for reading and stay eco-smart !
Query posed to chatGPT (aka Prompt Engineering Question)
I have two sets of measurements for my laptop using
sensorscommand in Linux. Both are taken 4 minutes apart. Can you format them in a table with three columns- column 1 with title "Parameter", Column 2 with "with ACAdapter" Column C with "Remove adapter +4 minutes.Please explain briefly what each parameter means? Try and answer question: What might cause the drop in CPU , GPU, and nvme-pci-0400 temperatures once AC charger is removed? Assume non-technical level of readership.
Specifications of the laptop in question
