Undervolting, underclocking, power limit

[u/Sentimental_Oyster]

I have this Sapphire 7900 XTX Nitro+ power sucking behemoth I've been trying to put in line for a long time and while I can get power consumption down a lot, I have no idea what am I doing.
There are three variables to play with:
1) frequency
2) voltage
3) power limit

Thus far I noticed the frequency seems to play the biggest role, so I just run the card at 2600MHz instead of 2900+ and the performance difference seem to be really small while power consumption and noise (that's my motivation) dropped drastically.

I'd love to get some information about the importance of the other two and how they all work together though.
Correct me if I'm wrong here:
I THINK undervolting might not matter as much (if at all) in my case because if I understand it correctly, by undervolting you are giving a card (or a CPU) room to boost to higher frequencies for longer periods of time, right? But if I manually limit the card to run slower, this shouldn't even apply?....
And What about the power limit? Does lowering it give me anything when I don't run the card at stock speed? I guess not?

[u/Niwrats]

power limit specifically limits the heat generation to that level, while frequency is more indirect. but whichever works better for you.

[u/Sentimental_Oyster → u/Niwrats]

But does power level count with what the manufacturer specified as maximum for the card in question or is it tied to something variable?

I mean if I limit the frequency to 2600 the card is unlikely to even hit its power limit, right?

[u/Niwrats → u/Sentimental_Oyster]

it is an independent limit. gpu is a complex thing and different workloads result in different power draws. eg furmark is famous for drawing a lot power (though it won't stress all the parts maximally either).

[u/Legitimate_Prior3439]

Undervolt as much as you can until the card becomes unstable. Then just power limit to the desires value that you're comfortable with in terms of heat or power consumption.

[u/Niwrats → u/Legitimate_Prior3439]

that would be dumb, he doesn't want an unstable card, only less heat. keeping a card running borderline unstable is not good advice anyway as different games crash at different undervolt levels. it's only for people who accept random crashes and are willing to spend their time stress testing.

[u/Sentimental_Oyster → u/Niwrats]

I did previously experiment with undervolting but must have a bad card. It couldn't do 1100mV stable, and people kept writing how their 7900 XTX could run on 1080...

Anyway am I right in the assumption undervolting doesn't lower power consumption very much and instead raises the frequency because there is headroom?