HOW TO CHECK HOW MANY CORE ARE BEING USED ?

First, it has to be said right at the top: while you may have inherited this system, it's bordering on criminal negligence for anyone to still to be running cf 4.5 (literally from before the turn of the century). If that's connected to the internet, the security risks are grave. Even an "internal system" is at risk of easy hacking by insiders.

So I hope you might be asking about your current core count and cf edition because you're assessing a move to a new, supported version (cf2023 or cf2021) or Lucee.

As for the core count, nothing in the cf admin reports that, nor is there a cf function for it that I can recall or find. I'll note that cf's ability to call Java can help here, but since you're on 4.5, I'll note that the ability to call Java objects was added in 4.51 (some think it was cf6, but that's instead when ALL of cf was rewritten in java). 

You can look at the cf admin to see both that version number and whether you are running cf standard or enterprise. I'm pretty sure I recall that even in 4.5 there was the cf admin "settings summary" and/or "system information" pages. 

I'm pretty sure it also had the cf "server" scope, which is a struct holding many values. Do:

<cfdump var="#server#">

To see what it shows.

Finally, you can find the cpu/core/processor count from your OS rather than cf, which may be all you need. Here's one of many resources showing how to do that, in windows, Mac, and Linux :

https://www.hivelocity.net/kb/how-many-cores-do-i-have/

Let us know if any of this above helps or if you still have questions.