ROME8D-2T + 3090s PSU requirements

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JediAcolyte

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May 29, 2020
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Wasmachineman_NL said:
Never use daisy-chained cables.
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Always!!

I've used half a dozen parallel miner board for large GPU compute systems and they've been very reliable for me. Just ensure you don't overload your psu.
With multiple 3090s, be very sure you have sufficient air flow to manage their heat output!
 
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RolloZ170

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Apr 24, 2016
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josh said:
Do I need to get a PSU with dual 4pins so that the board can supply enough power through PCIe
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the 8 pin and the 4 pin MUST be plugged even without GPU.
the connector GFX_12V1(near the battery) is the suplly for the GPUs PCIe, every power supply should have one.
for the GPU 2x 8pin you can use second PSU with "Slave PSU Switch"
but as JediAcolyte mentioned, the heat will be your BIGGEST problem( GDDR of the Turbo gets hot).
 
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josh

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Oct 21, 2013
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Wasmachineman_NL said:
Never use daisy-chained cables.
Click to expand...
Yup. Will be using the 16AWGs from Parallel Miner.
JediAcolyte said:
Always!!

I've used half a dozen parallel miner board for large GPU compute systems and they've been very reliable for me. Just ensure you don't overload your psu.
With multiple 3090s, be very sure you have sufficient air flow to manage their heat output!
Click to expand...
Did you use their full breakout board that bypasses the need for a primary PSU? Heat won't be a problem, using Delta fans for airflow in AC environment.
RolloZ170 said:
the 8 pin and the 4 pin MUST be plugged even without GPU.
the connector GFX_12V1(near the battery) is the suplly for the GPUs PCIe, every power supply should have one.
for the GPU 2x 8pin you can use second PSU with "Slave PSU Switch"
but as JediAcolyte mentioned, the heat will be your BIGGEST problem( GDDR of the Turbo gets hot).
Click to expand...
So the second 4pin isn't necessary? There's 2x4pins on the board beside the CPU.
 
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josh

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Oct 21, 2013
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RolloZ170 said:
i see only the 8 pin and one 4 pin.
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I think we are referring to the same thing. The 8pin is a 2x4pin for my PSU. It won't fit the VGA 8pin nicely so I put the CPU 8pin there.

But I'm starting to think I'm doing it wrong? There's another "optional" 6pin at the bottom which looks like it's for a VGA 6pin. They're all 12V rails anyway?

My PSU only has 2x4pins. I think I'll need to get one of this for the 3rd 4pin? 6 Pin PCIe to 4 Pin ATX 12 Volt Motherboard Power Cable - Parallel Miner

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RolloZ170

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Apr 24, 2016
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josh said:
But I'm starting to think I'm doing it wrong? There's another "optional" 6pin at the bottom which looks like it's for a VGA 6pin. They're all 12V rails anyway?
Click to expand...
the connector GFX_12V1(near the battery) is the suplly for the GPUs PCIe, every power supply should have one.
 
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RolloZ170

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Apr 24, 2016
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josh said:
I think we are referring to the same thing. The 8pin is a 2x4pin for my PSU. It won't fit the VGA 8pin nicely so I put the CPU 8pin there.
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the 8 Pin (EPS) AND the 4 Pin is for CPU only. PCIe is normaly supplied by the 24pin. because thats not enough there is an additionaly 6 pin near the battery. each GPU draws on PCIe 60Watts of 12V, makes a sum of 240W for 4 GPU, no way for the ATX24 connector(only two 12V wires)
 
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JediAcolyte

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May 29, 2020
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josh said:
Yup. Will be using the 16AWGs from Parallel Miner.

Did you use their full breakout board that bypasses the need for a primary PSU? Heat won't be a problem, using Delta fans for airflow in AC environment.

So the second 4pin isn't necessary? There's 2x4pins on the board beside the CPU.
Click to expand...

Yes. I have 4 of their zsx boards that are compatible with 1600w dell titanium rated PSUs.

Ensure you get airflow to the front and back of your 3090s. The gddr6x chips on the back get very hot and can drag down performance.
 
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josh

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Oct 21, 2013
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RolloZ170 said:
may work but: if your PSU don't have EPS connector i doubt its the right one for your plan.
whats your PSU model ? wattage ? (if not a secret)
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I'm using multiple 1400W Dell PSUs with a breakout board. This is the pinout. I believe there are 2x EPS for the CPU.
 
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josh

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JediAcolyte said:
Yes. I have 4 of their zsx boards that are compatible with 1600w dell titanium rated PSUs.

Ensure you get airflow to the front and back of your 3090s. The gddr6x chips on the back get very hot and can drag down performance.
Click to expand...
How would you connect these to the ROMED8-2T? I only see 2x4pin EPS while the board seems to need 3. Also, the specs of the breakout board says "180watts limit on wattage draw from the 24pins ATX connectors". That shouldn't be a problem for 200W CPUs right? Since those are not powered by the 24pins.
 
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josh

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RolloZ170 said:
the connector GFX_12V1(near the battery) is the suplly for the GPUs PCIe, every power supply should have one.
Click to expand...
Alright, so I plug a GPU 8-pin to that, what about the 8pin+4pin on the top? They're labeled ATX_12V1 and ATX_12V2. Is it sufficient to simply power ATX_12V1?
 
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RolloZ170

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josh said:
Alright, so I plug a GPU 8-pin to that, what about the 8pin+4pin on the top? They're labeled ATX_12V1 and ATX_12V2. Is it sufficient to simply power ATX_12V1?
Click to expand...
NO. you need 6 wires +12V for the CPU.
on the picture ALL 4 pin are sources from 2 wires(from ATX24) this is NO GO !
josh said:
the specs of the breakout board says "180watts limit on wattage draw from the 24pins ATX connectors".
Click to expand...
the 24Pin is never used to supply the CPU. on legal PSU the EPS and 4pin are sources separately.
 
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RolloZ170

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josh said:
Yup. Will be using the 16AWGs from Parallel Miner.
Click to expand...
the AWG is not all you have think about. one pin(contact) can not draw the power than the cable can.
i.e. there are only two(2) +12 in the ATX24 conn. an you are going supply 3 4Pin ? hope you see what's wrong.
 
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JediAcolyte

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These parallel miner boards are built for a specific purpose. Not yours, as far as I can tell.
They are designed for systems with super low power CPUs, loaded up with GPUs.
I would recommend using a standard PSU to power your motherboard, ensuring it has the correct eps 12v connectors. Then add on your parallel miner board and PSU to power your 3090s separately.
Or just buy this.

If your not adding too much else on there, you could power your board and 4 3090s, technically.
Personally l, I'd still go with 2 PSUs.
The YouTube channel GamersNexus did several pieces on transient spikes under load of high end GPUs and showed how they can double their current draw for short periods of time and have the PSU trigger it's ocp.
If you plan on using this much power in one small box you need to be very careful.
 
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