As said, the original vanilla version of BG1 uses up 1 processor core of my Windows 10 Lenovo Ideapad Gaming 3, while the rest remain unused.

This is expected behavior from an old game that wasn't meant for use with multiple CPUs.

However, it is infuriating to run a nearly 25 year old game on a modern machine and within minutes hear the CPU fan powering up to full speed. See, the sole core is heating up to 70+ degrees Celcius and therefore needs to be cooled.

But I hate overheating, hate fan noise.

Isn't there any way to keep the game from abusing the CPU knowing full well it doesn't need even a fraction of its power while sending it to the moon temperature-wise?

I found a single other thread that dealt with this. Unfortunately, there were no solutions, save setting the game to Win 95 compatibility mode. However, for some reason, it makes the game run incredibly slowly for me - I'm talking unusably slow, slideshow slow.

If no one can help with the issue itself, can somebody at least test whether setting original BG to Win 95 on a Win 10 produce the same problem for them - i.e. making the game run very slowly - so I can at least narrow the search field?

P.S. Please do not suggest using "Enhanced" editions. Thanks.

hahaha gotta suffer
lol

This is a common defect in older games. In an attempt to make the game as responsive as possible, it is constantly polling for any new user activity.Yes. The game needs to periodically sleep whenever there is no user input. From what I recall, the Enhanced Editions seem to have gotten this right. (Yes, I see that you don't want to use EE, but I still want to point out that it is fixed there. Maybe you'll decide that you hate the CPU spinning more than you hate the changes in the EE versions.) EE versions still use more CPU time than I think they should when idle, but it's nowhere near as bad as 100% of one core.

Your options are:
- Switch to a version where someone has fixed this. EE seems to have it right.
- Find/create a version where it has been fixed. A dedicated hacker could probably correct the Classic Edition in less than a day of work, once you got the rightsholder's permission to modify the game (or decided you don't care about modifying it in violation of the EULA).
- Run the game under a wrapper that forces sleeps at the appropriate time. This would be pretty easy for a Linux user on Wine. It's probably not practical on native Windows though.
- Bug GOG to bug the developers to fix this. I expect this to go nowhere, since EE has it fixed, and I doubt the developers want to do anything with CE.
- Use your OS tools to force the core to powersave mode. This won't stop the spin, but it will reduce the amount of waste heat it can generate.

Try using GemRB.Could you please post a link to this thread?

Thanks, I'll give it a try.
Here's the other thread that dealt with this:
https://www.gog.com/forum/baldurs_gate_series/100_cpu_usage_modern_computer_whats_up

Well, according to this post in the thread, the suggested solution is to disable the compatibility mode which is enabled by default in some games. As you can read further in the thread, this is not a valid solution for classic Baldur's Gate games because the compatibility mode is already disabled by default.

GemRB is a modern and open source implementation of the Infinity Engine: honestly I have never tried it, but I suppose it should enhance compatibility with modern systems.

Yes, I'm aware, since the current last and second to last comments in that thread were made by me :D
I've tried GemRB as per your suggestion. It's got some excellent features, such as the ability to easily Alt+tab out of it, perma-skip intros, running on any platform, the ability to use the scroll wheel and other quality of life stuff. For now I decided against using it since some of the stuff it adds infringes on the original game experience (such as auto-identification), but more importantly the game screenshots made with it are of inaccurate resolution. But for less obsessive people it's definitely a excellent way to play the original games without using EE.

call for help

My bad. Please, forgive and forget my oversight. Thanks for sharing these information.

Start the game then open your taskbar and set the processes to use a single CPU... That tells your laptop what you are trying to do and stops it overheating but it's less stable so expect a crash every hour or two

Of course running the EE build is the better option

Thanks. Interestingly enough, the process was already set to 1 core only by default. I changed it to all cores for experiment's sake. I could be wrong, but that seemed to even out the load between the cores, so possibly the laptop won't run so hot anymore.

Just set bgmain.exe to use all processors on "set affinity" inside task manager

How to Set CPU Affinity for a Specific App

Open Task Manager. ...
Click “More details” ...
Right-click the app you want to modify and click “Go to details”
Right-click the app in the “Details” window and choose “Set affinity”
Select the cores/logical cores you'd like to assign to the program.

My first hit for searching "task manager detail set affinity", with photos

https://winbuzzer.com/2020/07/03/how-to-set-cpu-affinity-in-windows-10-with-task-manager-or-system-properties-xcxwbt/

Sorry, I did not see this post, that's my solution for the heating problem.

I just pasted here the solution I posted on the other thread.

Evening the load across the cores solves the overheating problem for me, as the "100% on one core" problem is solved.

I don't know about energy comsumption, though.

Use Vsync = ON