Question regarding power limiting

t40r · April 13

Hey guys,

I'm pretty new to the whole power limiting world, so I wanted to share my experience and hopefully get some insight from those of you who are more seasoned. I’ve got a 4090, and with all the ongoing drama around the connector issues—plus the apparent benefits of power limiting—I decided to give it a shot today using MSI Afterburner. After a lot of reading and research, I settled on an 80% power limit. From what I gathered, it helps with thermals and doesn't sacrifice much performance. And I can definitely confirm that—temps are down, and performance.

I was monitoring everything using HWMonitor, and I saw my "GPU Power" drop from a max of 450W down to 336W. That lines up with what I expected. However, what confused me is that right below that, the "GPU Rail Powers" still shows a max of 617W. That seems... off?

So now I'm wondering—did I miss a step? Is this normal behavior? I didn't do any undervolting, just set the power limit.

Thanks so much for taking the time to read this and for any help you can offer! Apologies if this is a newbie question—just trying to learn the ropes

Imakuni · April 14

50 minutes ago, t40r said:

However, what confused me is that right below that, the "GPU Rail Powers" still shows a max of 617W. That seems... off?

So now I'm wondering—did I miss a step? Is this normal behavior?

It's normal, the GPU can have spikes of upwards of twice the usual power consumption for very brief moments.

t40r · April 14

5 hours ago, Imakuni said:

It's normal, the GPU can have spikes of upwards of twice the usual power consumption for very brief moments.

Ahhh! Okay so if I am understanding you correctly, the 336 watt (or so) should be what it stays at for the most part, but it may spike to that 600w every now and again? Damn this connector is awful..

Imakuni · April 14

6 hours ago, t40r said:

Ahhh! Okay so if I am understanding you correctly, the 336 watt (or so) should be what it stays at for the most part, but it may spike to that 600w every now and again?

Yes.

6 hours ago, t40r said:

Damn this connector is awful..

Well yes, it is awful, but in fairness, the card spiking isn't the connector's fault in the slightest. Even if you were using a bunch of 8-pins, it would still spike anyway.

t40r · April 14

4 hours ago, Imakuni said:

Yes.

Well yes, it is awful, but in fairness, the card spiking isn't the connector's fault in the slightest. Even if you were using a bunch of 8-pins, it would still spike anyway.

Thank you so much for this breakdown and replying also you may not know the answer and that is fine. Should I be undervolting the card in your opinion to avoid these melted connectors? (I know there is no silver bullet just trying to hedge my bets as much as I can atm), or do you think the power limit would suffice? This is all new stuff to me, and I'll have to research undervolting afterwards, however I don't want to let this card have some stupid BS happen lol.

Imakuni · April 14

11 minutes ago, t40r said:

Should I be undervolting the card in your opinion to avoid these melted connectors?

Messing with the voltage is effectively useless with newer cards, Nvidia just goes "nah, you're not allowed to control the card, we know better than you do". Just stick to changing power limit and call it a day.