Power Supply Looking to power two GTX 1080 Ti without a SFX PSU

[NinoPecorino]

You could look into something like this: https://www.hdplex.com/hdplex-800w-dc-atx-with-16v-63vdc-input.html

the real problems with the hdplex 800 setup is that it's a larger total volume than an sfx-l unit, it still uses a 24pin cable, and it costs 432 american dollars. that being said i'm definitely going to buy it.

 

[Valantar]

the real problems with the hdplex 800 setup is that it's a larger total volume than an sfx-l unit, it still uses a 24pin cable, and it costs 432 american dollars. that being said i'm definitely going to buy it.

That price tag is... steep.

Even with the larger total volume though, the separable pieces might allow for a more compact overall setup if you can find enough nooks and crannies to fit the pieces into.

 

[aquelito]

I have two hypotheses as to why that didn't work:

1 (most likely IMO): The motherboard doesn't generate on-board 5VSB, and as such doesn't trigger the logic to short the PS_ON pins when using that power source.

2 (still possible, and at least testable): the power button is a momentary switch, so it will only short out the PSU pins for a very short time, after which the PSU will switch off again. The motherboard, not getting an external 5VSB signal, will only have power for a fraction of a second while the button is pressed - if that, as the PSU is just turning on. This might not be enough time to properly initialize the power circuitry on the board to maintain the shorting of the PS_ON pin after the button is released.

Of course this is all guesswork. Did you try pressing and holding the power button with that board installed? If you have a multimeter, you try powering the board with the 12V input and checking for continuity between the PS_ON pin in the motherboard 24-pin and motherboard ground. If there's continuity, the motherboard does initialize the PS_ON signal, so your board should work, but might require a longer press to initialize fully.

1. Depending on the wiring, the power switch LED remains ON even when the computer is shutdown. Which means I have my 5V ON ??
2. To maintain the PS_ON shorted with a momentary switch was the very purpose of that PCB !

The original idea was based on an optocoupler.
My designer friend replaced the optocoupler by a diode-based circuit :



Any thoughts ?

 

[Thehack]

1. Depending on the wiring, the power switch LED remains ON even when the computer is shutdown. Which means I have my 5V ON ??
2. To maintain the PS_ON shorted with a momentary switch was the very purpose of that PCB !

The original idea was based on an optocoupler.
My designer friend replaced the optocoupler by a diode-based circuit :



Any thoughts ?

Thanks for sharing this.

I think I know the issue and I have the solution.

I will breadboard it this week and share it with you privately.

 

[aquelito]

You're the man