Laptop cpu temps are lower on battery mode, higher when plugged in


Nov 17, 2015
Hi everyone!

I have a gigabyte p34k (AUS) and it uses i7-4720HQ as the CPU.
I have used this laptop for 3-4weeks, so its quite new, and I am primarly concerned about its temperatures. I think (correct me if I am wrong) that the higher the temp it runs on, the life span of any pc component will decrease. My issue with this laptop is why are CPU temperatures a lot higher when plugged in, compared to having it running on battery mode. At home, from memory, I believe that temperatures would idle at 49-55 degrees celcius while plugged in. On battery mode, it is around 45c idle.

Currently at uni, (ambient temps are probably a lot lower right now compared to the past couple of weeks which is why the temps are so low right now), I suddenly saw my laptop's temp drop to a new record low. Those temps are:
On battery mode, cpu temp idles at 30-35c.
While plugged in and charging, it idles at 40-45c.
As you can see, the temps are still quite high when plugged in, compared to when it runs only on battery.

From what i have read, I believe that laptops which are plugged in and fully charged will stop charging the battery and allow the laptop run on AC. Or does fully-charged laptops utilise both the battery and the AC power? I came across a reddit article for an ASUS laptop model, which discusses about the performance decreasing when battery is removed and is only running on AC, and one of the responses was concerning how some laptop utilise both the AC and battery power for a full performance. The link for the article is at the very bottom for anyone who wants to check it out.
I wonder if that is the reason why temps are suddenly a lot higher, because more power/higher voltage coming from both the AC and battery power source being used, which results in producing more heat. But I just don't understand why if thats the case... when performance is unnoticieable when watching movies, typing and browsing through the web, regardless of whether it is plugged in or not. So maybe I should just use the laptop without having it plugged in, and just turn the laptop off to charge it. But this apprently causes a decrease in the battery life span from too many discharge/charge cycles. So in the end, I have to decide whether I should care more abouts its CPU or the battery. I would have gone with letting my laptop run only on battery, but the battery is non-removeable, so I can't replace it when it starts to die on me =/

I think in the end, I guess my question would be which life span will decrease quicker. The battery or the cpu? I want this laptop to last me 10 years... hopefully >.<. My initial thoughts on this would be that the battery would not last for very long compared to the cpu. So I guess I should prioritise the battery instead of the cpu?

P.S My laptop is always on a laptop cooler!

On a final note, was all this worrying for nothing and I should just continue doing what I always do, which is having the laptop constantly run plugged-in and fully-charged, and only deal with the problem when it actually happens. The only reason I am so concerned is because this laptop took quite a toll on my savings.

TLDR; should I worry about my laptop's cpu life span that is constantly running too damn hot when plugged in or should I run it on battery mode since it is a lot cooler then having the laptop running on AC power, but this will affect my battery life span from too many discharge and charge cycles. CPU life span vs Battery life span, where both is equally important to me?

Link to article on performance of laptop without battery vs with battery.



Nov 14, 2015

Normal, Cpu, graphics run a lower clock on batteries to save power, could change this behaviour in bios and control panel power settings, It's the power saving mode to make batteries last longer. Batteries are cheap compared to cpu's. as long as cpu never goes 75 Celsius plus, no damage will be had


Nov 17, 2015

Hi Mark!
Thanks for the very fast reponse!
I have checked the clock speed, and both (plugged in and on battery mode) are pretty much the same at 798hz according to open hardware monitor. I really have no idea how to make my "plugged in" cpu temp to match the "battery mode" cpu temp. Under processor power management, they are pretty much both the same besides the system cooling policy. Not sure how to do it though the bios. And yes, I normally have it on power saver, which actually does make a small difference to cpu temps from maintaining a lower clock. Otherwise, if there is no way of making my cpu temp go lower when plugged in, than I guess I will manage with it. OR maybe the sensor doesn't work right when the laptop is plugged in.
Anyway, thanks again!!
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