The 500w alone cost you about 40-70 bux a month depending on where you live. Then add the AC. With efficient systems you would be paying a tiny fraction of that since you wont need an ac.
Are you using direct to disk on all cams?
You can try using blue iris's new substream feature to lower cpu in the interim. The function is not 100 percent implemented and you may have some issues so proceed with caution only after reading the threads on the subject.
Looks like dropping the system down to 8 cores and letting it sit at 77% cpu seems to have fixed the issue. Weird. I have some Ryzen hardware lying around I'll put together later and see if that makes a big difference or not.