I have been building PC from random parts to use for distributed computing work for many years.
Here's a few things I have learned that your HP service guys will be missing, not because they don't know their job but because this isn't a normal situation. The cooling on your systems will be built for EXPECTED USE. NO manufacturer expects you to run your machines at 100% load 24/7.
ANY distributed computing work will push your CPU usage to 100% on all cores unless you tell the project not to. This generates a lot of heat, the sort of heat levels you can expect from running some CPU benchmarking software, except it does so constantly. The result is that your cooling system will be pushed to the maximum continuously. Many people, myself included, upgrade the cooling on their machines beyond the base requirements, not just to cope with the extra heat but to do so with much less noise. If your fans are making a grinding noise it means the fans aren't designed to run at full speed for extended periods. That being the case, the CPU cooler very likely isn't designed for that load either.
If you want to continue to run any kind of distributed computing work you have two options:
1- upgrade your cooling solution with better fans and better CPU coolers. There are many available on the market. If noise is an issue, such as with office machines, I suggest Noctua branded items.
2- reduce the heat load by reducing the work settings. Change them to not use all the CPU cores would be my suggestion as is will reduce the heat load without making it cycle up and down which changing the time allowance will.

The other source of intermittent noise can be your hard drives. If you have, for example, Western Digital Green drives they will produce odd noises at random times as they spin up and down. This isn't a fault, it's due to the power saving features of the drive. My daughter found it particularly annoying so I replaced her HDD with a WD Blue and she is much happier.

edit: in your service guy's defence, they will be contracted to maintain the machines AS SUPPLIED. Modifications for use outside the design considerations will not be part of their brief and could well get them into trouble.

There is another issue that has been raised by various IT departments in the past. Security.
BOINC in itself isn't a threat, it's just a scheduler and manager, and comes from Berkley University. The projects you can attach to BOINC are of more interest in that regard.
WCG is funded and operated by IBM and subject to the full measure of IT security laws which they take VERY seriously. There is probably more scrutiny and security evaluation of the BOINC and WCG code than there is of the Windows source code.

Also @bethwells, would you mind posting the model number(s) of the hp systems you are running? I could look them up and see what kind of cooling they have built in. Also, if they are SFF (small form factor) those really don't have a lot of good airflow in them. Maybe adding an intake and/or exhaust would solve the problems. Hopefully we can figure it out

Hello BladeD,
Why are you requesting the original post to be split to a new thread? There are responses to the original post, which make it tricky to split only one post and move it to a new thread.

Thank you,
ErikaT

Thank you for the clarification, BladeD. I have split the second issue into this new thread.

ErikaT