I used a dual Xeon workstation for a while and it used more power then my entire rack does now. I rebuilt my entire network this year and power consumption was a bit part of the planning process and I don't believe it limited me getting what I wanted.

best advice is probably to spend a little more and get more modern hardware which will be not only better but massively more efficient. C-States have come a very long way in the last 10 years or so. there seems to be a flood of older dual Xeon workstations on the used market and I think its probably due to their power consumption. they might seem like a bargain but you end up paying for it in power (also heat and noise).

I learnt towards intel for my servers but use Ryzen for my current desktop. but either way I think something more modern will be a lot better. I think intel's come out on top for efficiency but maybe that is just personal bias.

for numbers:

my dual xeon workstation idled at about 170 watts on its own
my current rack with network equipment/2 servers/a few pi's/etc... idles at about 140 watts

another tip is to set up homeassistant if your not running it already and get some power monitoring going(shelly products recommended). having data will help you make power decisions and helps with mindset.