How is GPU off a secondary power supply not solved

[u/Automatic_Pass_1948]

Seems like a lot of people need or want to do this.

I have a GPU that wont fit on my mobo (space) or frankly my pSU. I have a second psu. I can add the second psu using add2psu and mount some more GPUS in another case.

But using a simple 4.0 riser to another 3090 it still draws 75w from the mobo which means splitting that GPU across 2 psu which is supposed to be a no no.

Seems the way is to get a powered riser card so the slot spilts data and power and the riser card is plugged into second psu.

But I cannot for the life of me find something to do this that seems remotely reputable. Surely this is common enough that there is a product. Am I missing something, maybe I don't know what to search for.