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Buck Converter to Power Crypto Mining?

Lt.Dan

Solar Wizard
Joined
Dec 25, 2020
Messages
3,528
Location
Tulare, Ca
Hey guys, I've been dabbling in Crypto mining a little lately, and have built a simple little GPU miner. I've been doing tons of research and reading etc.

My question first needs a quick explanation. The entire rig, is powered by an ATX PSU, which supplies various voltages to various components. The most important, and most power consumption, is the 12v supplied to the GPU's via their 6+2 PCIe pins. ATX PSU's can get pretty pricey when you get into multiple GPU's, and their efficiency can be less than desirable (85-92%). This can be even worse when it comes to powering it via solar, because after MPPT conversions, then inverter efficiency losses, and then the efficiency loss through the ATX PSU can mean the 500w the actual GPU rig is drawing, is really ~630w. Just doesn't make much sense to go from DC -> AC -> DC.

My question is, does anybody know if they can power their GPU's (and the PCIe Risers), from a 48v -> 12v buck converter? These can be had much cheaper, and typically have a much higher efficiency (upwards of 95%). And you also dont have the loss of the inverter as well. My only concern is if the buck converter has any voltage sag, I'm unsure of how the GPU will react.

Obviously I will need to leave the ATX PSU to supply the other components with 12v, 5v, and 3.3v, but a much cheaper PSU can be used, and the draw will be much much less.

On a side note, I have found 48v ATX PSU on the internet, that are pretty much drop in replacements, but their price tag of $800-1200 is a little off-putting.

Please discuss :)
 
Yes.
Dc2dc atx power supplies are available.

Also they make atx breakout boards.
Yeah I have already found DC to DC ATX Powersupplies, but they are highly, highly expensive, and their efficiency claims are barely 75%. Seems like a garbage product to me.

I was hoping to power the low wattage stuff (mobo, CPU, mem, etc) with a normal 120v PSU, then run a DC buck converter LIKE THIS to power just the GPUs. Yielding a much higher efficiency.
 
Yeah I have already found DC to DC ATX Powersupplies, but they are highly, highly expensive, and their efficiency claims are barely 75%. Seems like a garbage product to me.

I was hoping to power the low wattage stuff (mobo, CPU, mem, etc) with a normal 120v PSU, then run a DC buck converter LIKE THIS to power just the GPUs. Yielding a much higher efficiency.
I remember reports of folks being disappointed with the Daygreen converters.
I just had a quick look and can't find anything better though.
 
Hey buddy did you get this going? I know HBPowerwall got his rig going about 5 years ago, but no updates since then. Also @BradCagle has done something similar and mentioned that he’s done so, but I don’t think he made a video of stepping down 48v to 12v with a step down converter and then running his GPUs. I’ve been able to power my mobo and an old RX 560 GPU with a 360w 48v to 12v step down converter and a 300w pico board from Amazon, but I think there might be voltage sag because I get a malfunction error when I try to add my 1660 super (I haven’t had time to test this though…). I know HBPowerwall also had issues powering multiple GPUs and his converter was twice the wattage of mine.314F92BE-17FC-4EAA-AECD-428A948FA006.jpeg
 

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Hey buddy did you get this going? I know HBPowerwall got his rig going about 5 years ago, but no updates since then. Also @BradCagle has done something similar and mentioned that he’s done so, but I don’t think he made a video of stepping down 48v to 12v with a step down converter and then running his GPUs. I’ve been able to power my mobo and an old RX 560 GPU with a 360w 48v to 12v step down converter and a 300w pico board from Amazon, but I think there might be voltage sag because I get a malfunction error when I try to add my 1660 super (I haven’t had time to test this though…). I know HBPowerwall also had issues powering multiple GPUs and his converter was twice the wattage of mine.View attachment 148251

I did a video using 48v to 12v ASIC Mining. I use quarter brick isolated DC/DC converters, I also have something similar with GPUs in my mining shed.

Does your DC/DC output 12v, or 13.8v?
Some hardware may not like much over 12v
 
I did a video using 48v to 12v ASIC Mining. I use quarter brick isolated DC/DC converters, I also have something similar with GPUs in my mining shed.

Does your DC/DC output 12v, or 13.8v?
Some hardware may not like much over 12v
I remember taking a reading when I set it all up, but can’t for the life of me remember what that was lol I’ll go take a reading in the morning when I’ve recovered from 3 am baby duty…if you wouldn’t mind sharing info about your GPU setup I’d love to compare!
 
I remember taking a reading when I set it all up, but can’t for the life of me remember what that was lol I’ll go take a reading in the morning when I’ve recovered from 3 am baby duty…if you wouldn’t mind sharing info about your GPU setup I’d love to compare!

This shows my GPU mining shed.

I've also done this direct 12v to the battery (actually 13.8v) my GPU's didn't mind the higher voltage, but that ASIC did not like it.
 
This shows my GPU mining shed.

I've also done this direct 12v to the battery (actually 13.8v) my GPU's didn't mind the higher voltage, but that ASIC did not like it.
Thanks, did some voltage readings today and my converter is putting out 13.07 volts w/o a load and 12.74 volts with the mobo + gpu load. Quite the voltage sag…
 

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I learned quickly that the regular buck converters have way too much voltage drop. I just ended up going to server power supplies and running off 240v instead. I've got quite the little farm going on now...
 
This shows my GPU mining shed.

I've also done this direct 12v to the battery (actually 13.8v) my GPU's didn't mind the higher voltage, but that ASIC did not like it.
Okay I see, you’ve got 3x A4000’s which are super efficient cards! And your mobo doesn’t take up much power either from what I saw on your other video. So I’m guessing you’re pulling about 200-215 watts from that 48v - 12v step down converter.

I’ll have to try again with my 1660 super because I have it on a PSU and it’s working just fine with the software saying 56 watts.
 
I learned quickly that the regular buck converters have way too much voltage drop. I just ended up going to server power supplies and running off 240v instead. I've got quite the little farm going on now...
Lt. Dan! (Sorry had to do it, I hope everyone can hear my great Forest Gump impression!) Thanks for confirming voltage sag on converters! I wonder if I can mitigate that sag with a 12v lithium battery or some capacitor setup like Brad had in his ASIC video. Do you have a posting of your setup? Have you ever run the numbers on the efficiency/power losses from converting dc to ac back to dc?
 
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Okay I see, you’ve got 3x A4000’s which are super efficient cards! And your mobo doesn’t take up much power either from what I saw on your other video. So I’m guessing you’re pulling about 200-215 watts from that 48v - 12v step down converter.

I’ll have to try again with my 1660 super because I have it on a PSU and it’s working just fine with the software saying 56 watts.


I have them set to pull 100w each, and then the mobo pulls something like 20-30w. I have 3 more A4000's to put in there.

This is the converter I'm using in the shed. It has no voltage drop, and it rock solid https://www.mouser.com/ProductDetail/826-ADQ800-48S12B-4L

But you do have to build a board for it since its a module. I like these isolated DC/DC converters because there's minimal chance they could pass the higher (48v) through to the GPU's


BTW, I have 3 1660 supers. I'm going to put them on a board with that 24v-12v DC/DC (the one I added a cap to). I'll let you know if it works,
 
Lt. Dan! (Sorry had to do it, I hope everyone can hear my great Forest Gump impression!) Thanks for confirming voltage sag on converters! I wonder if I can mitigate that sag with a 12v lithium battery or some capacitor setup like Brad had in his ASIC video. Do you have a posting of your setup? Have you ever run the numbers on the efficiency/power losses from converting dc to ac back to dc?
Haha, thats what the name is from. Been called Lt.Dan ever since the movie came out.

The cost of extra parts and stuff was what put me off, capacitors or high dollar converters wasn't worth the few percent in savings of efficiency. Not to mention Server PSU's are cheap to replace, and I can easily keep spares on hand. My rigs are also in a Shed, 150ft from my battery bank now, so the distance would kill it.

Just for numbers, I have 1 rig that pulls 488w, 8 GPU's. Its running server PSU's at 94% efficiency, so from the wall 519w. Then its being inverted from my Sol-Ark from 48v to 240 at ~95-96%, say 94% to be generous. A total of 552w being pulled from the battery to power these 8 GPUS. A loss of 64w total. Not the end of the world, and reality its probably less.

I just finished putting this rig together; 1x 3080 and 7x 3060's. Running off 2x 1400w PSUs. I make these cases at work and put together the rigs myself.
20221029_143005.jpg
 
The switching ATX power supply is probably already capable of accepting 48v DC input and switching it down to 12 and the other required voltages. Main concern would be that the input wires to the switching circuit aren't rated for the amperage it would pull at 48v but I doubt it.

I have access to plenty of server power supplies and will be needing a 48v battery bank soon so I can probably test this if you don't have a throwaway to use. I don't have the draw though to push the amperage limits, so the proof of concept wouldn't prove that you won't get smoke.
 
The switching ATX power supply is probably already capable of accepting 48v DC input and switching it down to 12 and the other required voltages. Main concern would be that the input wires to the switching circuit aren't rated for the amperage it would pull at 48v but I doubt it.

I have access to plenty of server power supplies and will be needing a 48v battery bank soon so I can probably test this if you don't have a throwaway to use. I don't have the draw though to push the amperage limits, so the proof of concept wouldn't prove that you won't get smoke.
I would imagine if you put 48v through the PSU you would just have to derate significantly to reduce amperage like you said. A 1200w PSU would probably only be good for 500w at most.

I would try if I had more time on my hands, but I also would be afraid of damaging sensitive (and expensive) GPUs.
 
The switching ATX power supply is probably already capable of accepting 48v DC input and switching it down to 12 and the other required voltages. Main concern would be that the input wires to the switching circuit aren't rated for the amperage it would pull at 48v but I doubt it.

I have access to plenty of server power supplies and will be needing a 48v battery bank soon so I can probably test this if you don't have a throwaway to use. I don't have the draw though to push the amperage limits, so the proof of concept wouldn't prove that you won't get smoke.

A typical switching PSU would take mains in, and immediately rectify it (usually full bridge) so mains * 1.4ish = 168VDC
Then use high frequency transformer to convert it down, and then rectify again.

Not sure it's even going try if you only feed it 48v when it's expecting 168v dc. But if you get one to work I would love to know which model!
 
A typical switching PSU would take mains in, and immediately rectify it (usually full bridge) so mains * 1.4ish = 168VDC
Then use high frequency transformer to convert it down, and then rectify again.

Not sure it's even going try if you only feed it 48v when it's expecting 168v dc. But if you get one to work I would love to know which model!
I don't think transformer is exactly the right terminology. I'm no EE but as I understand it it's a switching regulator it takes any higher DC voltage and switch it down as required, and that's what gives it the regular ability to accept 150-350VDC from worldwide mains.

I've just tried it with a 12v adapter like this and it powered up a micro form factor PC like you'd use for a firewall off 48v:


I will try a full ATX PC next.
 
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