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so I have my room setup to run off a dc battery, and the battery itself is charged via a solar panel. I currently use an inverter to power my pc setup but I would love to know if I can eliminate the inverter entirely and run directly off of the battery or dc power alone and if so how. thanks

Nura
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  • isn't there any psu I can use or any tweaks to make it work? I mean I know computer psu's run off ac that's the whole point, it's what i'm trying to eliminate, I was thinking there might be a possible way since the power supplies themselves convert that ac into dc again if i'm not mistaken. – Nura Sep 08 '21 at 17:39
  • You could theoretically modify your PSU but if you get it wrong by bye computer. How do do that is off-topic here. – DavidPostill Sep 08 '21 at 17:43
  • thanks again, if there is any chance it'll work I'm doing it – Nura Sep 08 '21 at 17:44
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    A web search for "pc dc power supply" yielded several suppliers. There's also this exact question over on the [Electronics SE](https://electronics.stackexchange.com/q/18098). – Engineer Toast Sep 08 '21 at 17:44
  • "isn't there any PSU I can use or any tweaks to make it work?" - No; Provided you didn't want to blow up your PC and/or burn down your house – Ramhound Sep 08 '21 at 17:46
  • thank you all for the great answers, I found some more over at [this similar question I stumbled upon just now.](https://superuser.com/questions/1016/can-i-run-a-computer-using-dc-power) I will definately look more into it. – Nura Sep 08 '21 at 17:51
  • Yes you can. Just buy a DC-DC power supply. See my answer below. – Keltari Sep 08 '21 at 19:22
  • @DavidPostill sorry, but that is incorrect. Not only can you run a PC off of DC, its actually not that uncommon. I have personally worked on DC powered desktops and servers. You just need a DC-DC power supply. You can purchase them online in ATX form factors. Servers, as well, but typically the manufacturer has to offer a DC power supply option, as server PSUs tend to be proprietary. – Keltari Sep 08 '21 at 19:26
  • There is a new PSU standard where the PSU only provides 12V and the mainboard generates all the other voltages. Such a board would be way easier to use on a DC battery (which by chance also uses 12V?). – Robert Sep 08 '21 at 20:03
  • @Robert that would be awesome – Nura Sep 08 '21 at 20:11
  • @Nura The problem is this PSU standard is so new the number of boards that use it and that you can buy is very very low. The last time I read about some months ago there were less than 10 boards available. But even without this PSU standard there are some computers (mostly business PCs) which use a similar approach as such a PSU is cheaper and more efficient. Last but not least there are mini PCs available that use an proprietary external PSU that often only provides one fixed DC voltage. Not sure if such PC could really be used with a battery but I think worth to be checked. – Robert Sep 08 '21 at 20:19
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    Does this answer your question? [Can I run a computer using DC power?](https://superuser.com/questions/1016/can-i-run-a-computer-using-dc-power) – Toto Sep 09 '21 at 07:54

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Technically yes.

Practically, with some difficulty.

DC to DC converters are indeed a thing, and PC DC Power supplies are also a thing.

The main problem is supplying enough current on each rail for a total power output. Those DC supplies top out at 250W and the fact that they don't easily give you a cost suggests that they are more expensive than conventional AC/DC supplies.

AC/DC supplies are easy to fit multiple outputs around a transformer from a single input that then gets regulated. DC on the other hand is a bit more work and I wouldn't expect a similar rated supply to fit in the same space. The reasons for that are mainly in the realms of electronics, but generally DC/DC supplies need an input, buck/boost regulator for each output, and then smoothing. All an AC/DC supply needs is a single transformer, some relatively simple regulation and smoothing.

Mokubai
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Yes, but it get a bit complex.

First AC to DC is simple and efficient 4 diodes make up a bridge rectifier and your done.

So the biggest problem is your PC has so many connectors inside and the PC power supply is designed to handle that.

As long as you can supply 12v,5v,3.3v, and you might need a small supply of approx 1 amp of -5 and/or -12v. I don't know if they have finally eliminated the use of negative voltages.

So you could use boost and/or buck converters to get the voltage from your batteries to the required voltages.

The one issue here is the number of amps you will need at 12v. You need to measure the current usage and size the wires accordingly.

The 4 pin molex connectors only have 5v and 12v so those are super easy. The sata ports also support 3.3v, but most devices just use 5v and 12v on the SATA power connectors so your mostly fine there.

The 4/8 pin connectors for the motherboard are all 12v so no issues here.

So the biggest problem is the 24 pin connector will have access to all the voltages.

Unless you have a crazy number of other devices your biggest issues are going to be aggregating the GPU,CPU, and 24 pin motherboard connectors.

The older 6 pin version officially provides a maximum of 75 watts (although unofficially it can usually provide much more) whereas the new 8 pin version provides a maximum of 150 watts.

So for each 8 pin plug you need 12.5amps. Now you need to add all of those up. 6/8 pin connector

The CPU connector looks like this: enter image description here

So if you had a 8 pin CPU connect on the motherboard, and 2 8 pin connectors on your GPU that is already at a potential of 38 amps.

The situation is going to get worst from here.

You will have to be really careful as you could potentially be dealing with 60 amps, and required 4,6, or 8 gauge wire. One short circuit here and you have a major problem.

enter image description here

Since the Molex power connector is rated at 6 amps per circuit, with 20-pin part you should not draw more than 12A from 3.3V, 24A from +5V and 6A from +12V (note that pin 11 is often used for 3.3V remote sense). The 4-pin 12V2 connector P4 is rated 8A/pin, so you can additionally draw up to 16A on +12V. A simple math shows that with 20-pin main and 4-pin 12V2 aux connectors your maximum power could be 355 watt from https://www.smps.us/20-to-24pin-atx.html

This connector should help: enter image description here

Apparently as other users found you can buy DC-DC power supplies, but they seem to only have a 60-74 efficiency at least at the 750w range which you would want for a modern PC plus future upgrades.

cybernard
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Yes, you absolutely can run off of DC power. Google DC-DC ATX power supply units. Here is an example. DC power supply units are not common, but are often used with computers connected directly to battery backups and areas where connection to the AC power grid is not available, such as boats. You just have to make sure your DC supply is capable of supplying the necessary voltage and amperage.

Most people will never see these. But they are common in military and naval operations, where there is no AC power available. You will also see this for in television and radio broadcasting, but it is not as common and is being phased out.

Keltari
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