Can I run my CPU at 100% usage for a long time?

I have a Dell XPS 15 9570, 32 GB ram, 2.2 ghz and 6 cores. When i use an application (The parsim command on MATLAB) (for more details) then my fan starts running fast , during this my PC doesn't seem to be heating but it never got this noisy in the past so it got me worried. In my task manager , the CPU usage shows 100% when this application is running.

1. Is it a problem for the life of laptop, if I run the PC at CPU 100% for like 4 hours in a day?
2. Do I need to be worried about the noisy fan during the application?

tl;dr– Issues like overheating and excessive wearing can be important considerations for computers that handle heavier loads.

A lot of folks do run their computers continuously at ~100%. This is common practice in computational work, e.g. with engineering simulations or data analysis.

There're two common things to watch out for:

1. Overheating:
   Is your CPU, GPU, motherboard, RAM, disk, etc., getting too hot?

2. Excessive wearing:
   Is a piece of hardware that can get worn out being used too much? For example, some consumer disk drives aren't made to be constantly reading/writing data.

1: Overheating issues.

1. CPU overheating:
   In most cases, most heat will come from your CPU – which'll likely be the concern if you're observing 100% CPU usage (which is different from 100% GPU usage, 100% disk usage, 100% network usage, etc.). So, monitoring the CPU temperature is usually the initial focus.

2. Motherboard overheating:
   A related issue is the motherboard's temperature. A lot of folks ignore it and assume that it's probably fine as long as the other hardware temperatures are in-control, which seems to be a reasonable guestimate in most cases so long as there's also good air circulation inside of the box. This can be more dubious in the case of compact devices, e.g. laptops.

3. GPU overheating:
   GPU temperatures can be a big issue for folks who make heavy use of the GPU, including gamers, graphics professionals, and those who use GPU's as computational co-processors. I think I've seen even little Flash games in a browser go hard on a GPU, presumably due to inefficiency.

4. RAM (memory) overheating:
   RAM (memory) temperatures can be an issue especially with highly overclocked RAM. Some vendors'll sell fans with their high-frequency RAM for this reason.

5. Disk overheating:
   Some disk drives, e.g. 15,000-RPM hard disks, can have trouble with overheating. I haven't heard of overheating being a big problem with most lower-speed hard-disk drives (HDD's) and solid-state drives (SSD's).

There're other heats that one might watch out for, e.g. a heavily used server might watch out for heating on its network card while a computer with an embedded radio device might watch out there, but those seem to be less common sources of concern for typical users.

2. Excessive wearing issues.

1. Disk wearing:
   Most^{(I think?)} disk drives aren't made to be continuously used at max capacity. So if you have an app that's constantly maxing out a disk drive, e.g. if it's constantly rewriting log files, then that might be something to check into. Servers and professional workstations often have disk drives designed to handle heavier loads.

2. Fan wearing:
   Cooling fans continuously running at max might get worn out. A complicating issue with fans can be that if one wears out, but you don't notice it or monitor the related temperatures, then something might get excessively hot before the fan's failure is noticed.

Power-supply unit (PSU) wearing can also be an issue.

Discussion

If your CPU is running at 100% in short bursts, I wouldn't typically be too concerned by that in most cases.

If it's a common thing for your computer, especially over long time periods, you may want to understand the associated heat and wear issues. Professional users, gamers, and other power users often design their own computers specific to their anticipated usage.

In theory, so long as a computer can keep itself within tolerance as to temperatures, then it should be able to do that 'forever'.

In practice, laptops tend to struggle with the keeping cool part and even some desktops have poor airflow characteristics which will result in long-term heat build-up.

If your machine can stay within tolerance, then all you are really doing is shortening the life of the fans.