How is power distributed between GPU and riser?

[nu1mlock]

Hi,

Does anyone know how power is being distributed between GPU and riser?

Let's say a GTX 1080 Ti uses 250W at stock. How much of that power goes through the riser? If I lower the power limit to 50%, will the riser use 50% less power as well or will the riser always use the same power while only the power through the connectors to the GPU get lowered? How is the power divided among riser and pin connectors?

Thanks

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[percy_tc]

PCI-e slot is designed to deliver max of 75w.

[nu1mlock]

PCI-e slot is designed to deliver max of 75w.

Yes, but will it ALWAYS deliver 75W? What happens when I lower power limit with 50%.

[Vann]

I have a RX 480/580 dual PSU setup where the same PSU that powers the motherboard also powers all of the PCI-E 6-pin risers and the secondary PSU only powers the PCI-E supplemental power on the cards. Risers use between 40-50 W each. How much power is drawn from the PCI-E slot depends on the card. Some cards are configured to draw more from the slot than others. Lowering the power limit by 50% will definetly not lower the power draw from the riser by 50%.

[TheHas]

PCI-e slot is designed to deliver max of 75w.

Yes, but will it ALWAYS deliver 75W? What happens when I lower power limit with 50%.

My understanding is that some cards draw different amounts from the riser slot. AMD apparently used to pull more, but the latest drivers from both NVidia and AMD supposedly try and pull less from the slot (read this from a different article, but can't verify).

I think most power gets drawn from the direct cable plugged into the top.

It's not perfect but you can feel the riser and cables to see if it is getting too hot if you think it is drawing too much power. Mine are a touch warm, but not hot. I use NVidia 1060s and 1070s and power limit to 65-70. 

[Ledipaa]

If riser would take anything between 40W to 75W it sure doesnt sound good for the SATA power cables from where it comes Anyway, im using same cable for 1 or 2 cards.

[nu1mlock]

I'm not worried about the cable itself.

I want to know what happens to the power at the riser when I lower/increase power limit. Where does the GPU's pull power from "first"? Where will it "remove" power draw from first when lowering power limit? What does the added power go through first when increasing power limit?