Using two power supplies in one system?

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chizrah

chizrah

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Jun 25, 2016
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Hi there, I was wondering how I would go about using two PSUs in one system (one for GPU only, another for all other components). How would I set that up?

Also, yes, I know it's sketchy, and no, I can't do anything about it.
 
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J
If you can somehow prevent your 770 - **and everything else** - from drawing from both PSUs simultaneously, then you can do it.
But nothing - and I mean nothing - should be connected to both PSUs. (positive OR negative) A common ground is fine, but that's it.
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Can it be done? Yes.
Is it a good idea? No.
Will you let the magic smoke out? Maybe.
 
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It's usually cheaper and safer to just get a good PSU, unless you're looking at 1000+ watts, in which case I'm really curious about what you need it for, as any 1000W+ system requires a budget big enough that the extra cost of a big PSU would be negligible.

But regarding your question, yes, it can be done, as has been stated above.
To make it even sketchier and cheaper, you could just bridge the green conector with a black one on the second PSU, which will force a permanent ON state. Then, just switch off the PSU from its own switch. Not guaranteed to work 100%, but I have certainly done this a lot to check many generic PSUs, or use them for non-PC related applications. Cheap generic PSUs are a great cheap source of stable, high current 5V energy.
 
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I've already looked at add2psu and I'm kind of on a tight budget, so it isn't really an option. It's not about the wattage, the reason I need to do this is because I recently got a HP PC which I'm planning to add my 770 to. But the power supply is only 320w, so I need to upgrade it. Here's the catch: I must use the old PSU as well because all of the connectors on the motherboard are proprietary.
 
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Well then any type pre-made device is outta the question. You'd need a circuit diagram to work out what two wires you'd have to tap to relay the ON signal to the 2nd PSU.... but even buying the wires, connectors and tool necessary to do the job would cost more than the $13 for the Add2PSU
 
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Are you sure about that? Sometimes they use proprietary PSU connectors (which there are adaptors for that) but other than the the connectors would be standard otherwise the whole system would need proprietary hard drive, cd drive, etc. What specific model is it? Maybe some links?
 
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Oh man,

I've seen some split up setups (Like dell splits it to 2 cables) but that is just plain ridiculous. I have never seen anything like that! And yeah other than using add2psu which uses a molex connector to turn it on and off there really is no simple safe way to do this. I searched high and low for an adaptor and came up with nothing. Some guys did rewire their aftermarket PSUs to the plugs form the stock one. I think that is an unsafe idea.

Add2PSU is 13 bucks, its literally the only way to do this safely, I understand you are on a budget... but its 13 bucks.
 
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You get what you pay for. £30 is worth it knowing you won't damage your equipment or burn your house down.
 
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If done correctly, a proper bridge between the correct connectors (green+black) from the second psu will be enough and safe. The only catch is that you would have to turn on and off the second psu manually.

I recommend to buy the £30 part or some other high quality equivalent. But I guess that the HK cheap part is even less safe than my method.
I insist with the bridge method not because it is the best, of course it isn't. But given the choice between a cheap unknown part and in the bridge method where you know exactly what is going on and there are no 'hidden' risks, I'll choose the bridge. It's only a high impedance control signal (5v), negligible current. Just isolate the bridge so that it doesn't short anywhere.


Do you know some electronics, or know a friend who does?
 
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Two PSUs are possible, but I would not try to combine them in any way.
First, when two PSUs are in the same path, any voltage difference between the PSUs will result in current draw. This is not only inefficient, but could damage whatever else is in the circuit.
Second, when a voltage is supplied by two parallel supplies, the current tends to go through one, rather than both. This means that one supply will do all the work, and could even burn out, while the other one just sits there looking pretty. Parallel supplies rarely work out.
Instead, you would want them to share a common ground, but separate the current paths as much as possible. This means that, while one PSU could power the Motherboard and any expansion cards installed, the other could power all peripheral components: fans, drives, card readers, etc.. If you're careful, you could even rewire your USBs to supply voltage with the 2nd PSU - reserving all the 1st PSUs available current for the MoBo/CPU/Memory/expansion cards.

There's another option. Take it to a qualified electronics tech. He could resolder the proprietary cables into a new PSU. Any qualified tech should be able to do it with just a solder pen, a voltmeter, a pen and a pad of paper. Darn nearly 100% of the time, a "proprietary" PSU is just a standard PSU with a couple of odd connectors attached.
 
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If you can somehow prevent your 770 - **and everything else** - from drawing from both PSUs simultaneously, then you can do it.
But nothing - and I mean nothing - should be connected to both PSUs. (positive OR negative) A common ground is fine, but that's it.
 
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Just a bump, for anyone who still cares. As anbello suggested, I'm bridging the pins and just manually switching the second PSU off and on, and it's been working perfectly for months. I've yet to have any issues with it. The only things that the second power supply is plugged into are the 6+8 pin on my GTX 770. At some point I'm planning to upgrade my motherboard and CPU, be it Ryzen or whatever comes after Kaby Lake, so for now, it's fine. Thanks guys :)
 
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Glad you have it working.

Just as an FYI when you are ready to replace your motherboard theres a good chance you will need to get a new case (and can eliminate this setup) as HP tends to use proprietary screw patterns and sometimes even motherboard dimensions in their cases.
 
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badjona7an said:
Hello there, I have an interesting issue with my PC and while digging for info on how to fix it I came up to this threat. So basically two video cards, each one been fed by a separate power supply, different single rail design PSUs, main one is 54A according to specs but it's platinum and last time it gave up at 800W drawn from AC if truly 92% efficient should've been 62A @ 12v and second one I think was somewhat 47A. Anyway, everything works perfectly fine until I turn on Crossfire and put up some load on I start getting some popping noise out of my PCI X-fi sound card which happens to be in between both GPUs. To me it seems to be something like a ground loop but it can be something else because it is present only when I enable crossfire and my knowledge definitely not enough to figure out the problem without committing direct experiments, so any ideas?
Click to expand...

You need to start a whole new thread for your particular issue.
THis one is 2 years old, and your issue is different.

Thanks.
 
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