X1 Carbon Gen 7 fan running constantly

New to the forum and came here because there isn't much activity at the Lenovo forums. I'm hoping some users can share their experiences with this laptop. I have the i7-8665 CPU. I am using the laptop most of the time plugged into AC via a USB-C cable through my LG monitor. I have also used it with Lenovo Thunderbolt dock with the same experience. Windows mode 'best battery life' is quiet but too laggy for my work. Windows mode 'better performance' and 'best performance' is good for speed but the fan is running constantly, even when there are no tasks and it should be sitting in idle. My work is mostly Outlook, Excel, Word and Chrome. Nothing too terribly taxing. I don't get why this laptop runs the fan so much. I reached out to Lenovo support and they requested I send it back for service. Before I relinquish the laptop to them for some unknown period of time, I wanted to know if others experienced this issue? Or am I unique and should return it?

 

Two part post. First the reality is for a vast majority of notebooks the fan will always run. Only a handful I can think are exceptions to that rule especially when in use with an external monitor and only under very specific conditions. Examples include high end workstations like my Zbook Studio G5, Most Alienware laptops using Optimus (Not Gsync) and Macbooks. Anything else is a crapshoot and should be investigated on a case-by-case basis.

That said Lenovo has a poor history for good thermal solutions with the X and P series being the worst offenders. I owned a 6th gen and very rarely was the fan not running at some level of speed, this was after replacing the thermal paste with liquid metal mind you; granted it was at a lower rate of speed but you get the point. My guess is that your complaint has to do with the high pitch of the fan or it being close to full speed most of the time. If that is the case then you can try something like liquid metal to improve thermal contact but that will only mask the real issue. The real issue being the laptop is too thin and the thermal solution chosen by Lenovo is not adequate to keep that device cool without running the fan near max 24/7.

If this is a concern to you send it back and buy something else like the devices I mentioned.

 

What I don't understand is why the laptop runs cool, quiet and fast when not plugged into AC. To me, it's something to do with AC/charging that is causing the fan to go into overdrive off and on throughout the day.

Second question - does running an external monitor put more or less of a burden on the processor? Note, I'm using a 4k monitor and have the X1 with the 4k screen.

 

Battery and AC power/clock curves are different. For the X1 since it is using the integrated graphics card on the CPU more, normally running an external monitor especially a 4k version would trigger the discrete GPU to engage which again will increase heat and power draw.

 

I have an X1C6, and it gets quite hot while charging, too.

I'm not worried about it, but I should note in the BIOS/UEFI, there is a setting for performance modes while on battery and while on AC. By default, battery will be "Optimized" (iirc), while AC will be "Max Performance." Maybe setting that to Optimized will help?

As for the 4k external display, there is only an integrated graphics processor for the X1 Carbon series. Right now, it's the ~5 year old and severely underperformant Intel UHD620. The GPU is barely capable of powering a 4K display without stuttering, and sometimes it fails at that. To put it nicely, Intel lobbed a stinker with the UHD620, and we've been stuck with it (named the UHD520 at release). Running an external 4k display, it will be depend on your setup. Does your laptop already have a 4k internal display? Is it disabled when using the external 4k display (basically, are you driving two 4k displays at once?)?

I KNOW I didn't really answer your original questions directly, and I'm really responding to Sentential, so please re-ask or re-phrase them if you want me to answer them.

EDIT: so one of them is: Windows "Best Performance" setting keeps the CPU at max clocks and disables most/any power saving method, resulting in a hot computer. Really not needed for the current crop of CPUs, yours included.