Here's an example:
I wanted a PC to run
Blue Iris exclusively, and needed another new PC to run Photoshop/Lightroom. I found two Dell XPS 8920 Desktop I7-7700 16GB RAM 2TB HDD, used on EBAY (refurbs). They both came with the 16GB RAM, but I added another 16GB to the "photoshop" machine. I also added a 4TB WD Purple drive to the BI machine.
I bought a 1500 Watt rated sine wave Cyber Power UPS to run both of those machines as well as their monitors. Right now, the cameras, their POE switch and all of that other stuff is on a separate UPS along with another PC that is about 10 years old, that I built using a 6-core AMD processor. That system had been getting extremely slow running Photoshop, and needs to have a clean re-install of Win 7.
The UPS has a display that shows various parameters, one of which is the wattage currently being consumed by whatever is connected to the "battery backed" AC outlets. I leave both of these new PCs running at all times with NO power saving enabled. So they actually run all of the time, never sleep, doze, loaf, or whatever they call it. I don't ever use a "screen saver", I just let the monitors sleep (black screen).
So, with both of these machines on and running, Blue Iris minimized, and the other PC doing nothing (although, they never really do "nothing"), the power consumption for the two machines and their sleeping monitors is showing as 30 watts! That's amazing to me because when I have checked my older machine, it uses around 200 Watts (just that one PC) when sitting idle.
So these newer PCs really are amazingly power efficient. And that saves on the power bill, especially for someone like me who leaves them on 24/7. But in addition, it means that if there's a power failure, the "run time" on the UPS will be a LOT longer than what it would have been for the old PC.
So now, rather than cleaning up my old Win 7 PC, I will probably find another refurbished newer PC to take its place. It's just not worth messing with anymore.
I need to see what the power consumption goes up to when I'm working the Photoshop PC hard, crunching on, for example, a video clip converting "frames to layers" or batch converting a bunch of RAW files, etc. But since most of the time, things will be running just the way they were when I made that test, the power consumption under "hard use" is largely irrelevant. And the length of time I'll get running on the UPS before its battery runs down will almost certainly be under those same conditions.
As a side note, Photoshop will also make use of the Quick Sync features in the newer Intel PCs, and I have that enabled on the new (to me) PC. It's a huge amount faster than the old PC despite having 2 fewer cores in the processor and having a similar main clock frequency compared to my old machine. I'm very happy that I upgraded.
fenderman is right. I think you'd be highly impressed and quite happy with a newer, more efficient PC rather than trying to make the one you've got do what you need. The Quick Sync graphics processing built into the newer Intel processors is well worth having, IMO.
Oh, and running 7 cameras at 15fps, Five of them 3MP, and two 2MP, I usually see about 13% CPU usage. That goes up to 15% or so when I have the GUI showing and I'm rooting around with things.
I'm still not especially thrilled with Win 10, it'll take some getting used to, but 7 will eventually be obsoleted by MS, so I guess I need to get used to 10, anyhow.