I bought the AM5 motherboard so I am officially moving to AMD after 30+ years of Intel. Thanks for all of the advice.
As you like to keep your CPUs tuned to be efficent, I really suggest you look into PBO + Curve Optimizer (negative offset) which is the most efficient undervolting you can do on Zen 5.
Here is a good layman's introduction to PBO + negative offset Curve Optimizer. The video is about Zen 4 but it's similar with Zen 5 just with even more options. It goes through the basics, the most important BIOS options including the power limit and voltage limit (PPT):
Here is a bit more technical overview of the undervolting options on Zen 5 (Curve Optimizer + Curve Shaper) The Curve Shaper is" the new kid on the block" for Zen 5.
Curve Optimizer and Curve Shaper are not the only ways to undervolt your Ryzen CPU. You can also undervolt by lowering the temperature.
skatterbencher.com
He has a different video on the subject, but it's best to be already familiar with the other PBO options:
With Curve Shaper you can make higher negative offsets stable than before (as they would previously crash when idle or at light loads, due as the voltage was too low.
The video mentions this, but I'll still reiterate. Bare in mind one of your
CCDs is binned for max clocks, the other one for efficiency, so the optimal curves for both will differ! That means don't try all core offsets, rather do at least CCD (or per core, if you have the patience).
So to recap. With PBO you'll get to the set the max allowed voltage, amperage and temperature for your CPU and let it boost to the optimal clocks for each workload within those constraints You don't put arbitrary limits but tune the entire Voltage/Frequency curve. "ECO mode" is nothing different. It actually sets the same PPT/EDC/TDC values. I wrote about it here:
Does anyone have a non-X AM5 CPU that can look in the bios to see if ECO mode setting is available, and if it is does it do anything? Any ECO Mode info I found was for CPUs ending in X. On AM4 APUs, you could ECO Mode them from 65W down to 45W, which was useful for a system that you intended to...
forums.anandtech.com
So you can limit the CPU to any wattage you like. With these (and good cooling) you can really tune the CPU to sip power and still run fast (in all likelyhood faster than stock).
My 5800X3D for instance has done stable -30 offset for all cores a little over 2 years by now. And it made a hell of a difference. Out of the box it's straight up to 95 degrees with all core loads (e.g cinebench). With PBO It actually runs 100-150 Mhz higher (all core) and only jumps to ~79 degrees slowly going up to 86-87 on long stress-test runs. While gaming the CPU power draw can be as low as 50-60W (at 4.5 Ghz)