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Problems with power supply and motherboard compatibility appear to be common.

Are there any computer components that could be placed somewhere between the PSU and wall outlet to minimize the chance that the power supply will blow the motherboard and vice versa? For example, would a surge protector, redundant power supply, or uninterrupted power supply be of any use here?

Suppose you disconnect your machine's motherboard from its current PSU and then connect it to a new PSU that supplies a lot more power. What can you do to make sure that your motherboard doesn't get damaged by the new PSU or fail to power on?

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It's hard to understand where you are going with this. Is there an actual problem you are trying to resolve? Or is this hypothetical? –  CharlieRB May 28 at 11:36
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electricity is like water in a pipe. you can't put more of it into a system than is being drawn out of that system. So your PSU power capacity will not fry the motherboard unless the motherboard is experiencing an issue that causes it to draw more power than is safe through a specific component. But also like a pipe, if you fill it with acid (bad power) it will eat away at the pipes until the system breaks. morale: make sure your PSU and mobo are both working correctly, and you will be fine. –  Frank Thomas May 28 at 11:52

6 Answers 6

up vote 4 down vote accepted

Suppose you disconnect your machine's motherboard from its current PSU and then connect it to a new PSU that supplies a lot more power.

That's not how electricity works. The nominal power is the maximum amount of power PSU is able to deliver. It's not the PSU that delivers constant amount of power, it's other components that draw power from it.

At any time your hardware will receive as much power as much is required, unless it's more than PSU's nominal power, in which case something will fail. Connecting your MoBo to a new PSU with higher nominal power won't cause computer to draw more power.

The best way of preventing PSU-related failures is not being cheap and buying a sound PSU.

  • High quality PSUs have better failure protection mechanisms.
  • They provide more stable voltage, thus making your MoBo last longer. (Damaged capacitors are probably the most common cause of MoBo failures and they are caused by unstable voltages on PSU)
  • They are quieter.
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Answer looks clear to me. I was wondering if buying a redundant PSU would meet the criteria of a sound PSU you listed, particularly the first bullet point? They are considerably more expensive though. I lost data during a power outage last night, so it seems to be worth the price. –  mobile computing May 28 at 12:17
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Redundant PSU is used when the main one doesn't supply enough power, which is not a problem here. Hardware damage happens when a high voltage spike passes through the PSU. Adding second PSU will only double the risk, because there will be two possible ways for the spike to go through. For protection of this kind you should use a surge protector. They are a must-have, especially in areas where blackouts are common. It's important to replace them every year, because they quickly become less effective. –  gronostaj May 28 at 12:36
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If you're concerned about your data, then instead of experimenting with PSUs you should start making backups. Follow the 3-2-1 rule: make 3 copies of important data, use 2 different types of storage and keep one of those copies off-site. There's no way to completely secure a hard disk from external damage (and sometimes they fail for no good reason too), backups are the only way to make your data (almost) perfectly secure. –  gronostaj May 28 at 12:39
    
@gronostaj Actually, aren't redundant PSU setups more about hot-swap capability? You add redundancy so if one fails it can be swapped out without impacting the system's functioning. Consequently, at most N-1 PSUs must be able to provide the power needed to run a N PSU system. But now we're getting onto Server Fault territory. –  Michael Kjörling May 28 at 13:02
    
Redundant power supplies are specifically for servers that support them, you can't just add one to your home PC. –  JamesRyan May 28 at 16:05

Having power protection between the outlet and the computer is ALWAYS a good idea. This protects from power spikes, like surges or lightening strikes.

As far as the PSU blowing the motherboard; a PSU only provides the power drawn from it by the components. It does not push a constant rate of power to all components connected. So the chances of a PSU blowing the motherboard are unlikely.

It would be interesting to see the facts behind your statement "Problems with power supply and motherboard compatibility appear to be common.". In my experience, PSU compatibility tends to be the purchaser error, not faulty equipment.

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I was conscious of that, not writing out the facts to support my statement. Lazy maybe, but there's a bulleted list of questions that follow my claim. In those questions, what I see is problems about motherboards and PSUs. –  mobile computing May 28 at 12:05
    
Thanks for the suggestion in the first sentence. So a surge protector and uninterrupted power supply can be useful here? I had a motherboard or two go up in smoke, depending upon what PSU I connected to it. I don't really know the reason why it happened. I'm not here to argue, either. I guess it wasn't the PSU, after all. –  mobile computing May 28 at 12:09
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Yes. It is ALWAYS useful to protect your equipment with some type of surge protection. If you want to avoid power related issues, you can spend the money on good UPS or even a power conditioner if your electrical source is unreliable. –  CharlieRB May 28 at 13:12

The nominal rating of a power supply is just an indication of how much power your motherboard can draw from it. If your motherboard works fine with a 250W power supply, there is no reason for having trouble with a 1000W power supply, as long as they were built for the same form factor (AT, ATX, etc). The form factor specification determines which voltages the power supply should provide for every connector pin. And, of course, these voltages must be independent from the power supply power rating.

Said that, a flawed power supply could eventually put a higher voltage over one or more output pins. If that voltage difference (between the specification and the voltage that power supply is providing) is too high, the motherboard is going to be damaged. Some motherboards have an anti-surge protection built-in. Which will prevent this kind of damage.

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Are there any computer components that could be placed somewhere between the PSU and wall outlet to minimize the chance that the power supply will blow the motherboard and vice versa? For example, would a surge protector, redundant power supply, or uninterrupted power supply be of any use here?

No. Based on the emphasized part.

Don't get me wrong, there are many very good reasons for putting a surge protector or voltage-stabilized uninterruptable power supply (UPS) in the computer's AC mains feed line, and in fact I'm pretty sure I lost my previous computer to unfiltered AC. But something like that will not prevent computer-internal damage caused by a faulty or malfunctioning (computer-internal) PSU, because the surge protector cannot know whether the current draw is a result of normal but higher-powered use, or if it is the result of a malfunction. I believe most surge protectors are overvoltage protectors, not current surge protectors (also known under the term "fuses"). It is also important to put everything that is hooked up to the computer on equally good protection; while not very likely, if a voltage spike can jump through your printer to the computer, the fact that the computer is on a filtered power supply won't help much. Many years ago now, I had a CRT monitor kill a motherboard through the VGA cable through the graphics card.

Suppose you disconnect your machine's motherboard from its current PSU and then connect it to a new PSU that supplies a lot more power. What can you do to make sure that your motherboard doesn't get damaged by the new PSU or fail to power on?

You go the extra mile, pay a bit of a premium and buy a high-quality PSU.

An electrical component -- any electrical component -- will only draw as much power as it needs from its power source. The power source must be able to supply the amount of power drawn by the component at a voltage that the component can work with. Consider the lightbulb you hook to the same wall outlet that can just as easily power your hairdryer or vacuum cleaner, both of which can draw on the order of 100 times more power than a lightbulb. (Kilowatt range rather than tens of watts.)

The power supply rating tells you (one part of) how much power the power supply is capable of supplying. (Another very important aspect especially in high-powered setups is the power supply per-rail capacity. A third aspect is the amount of power it can supply at various voltages. The two latter are very often closely related but they are not necessarily the same.)

A high-quality power supply will contain circuitry in addition to what is absolutely necessary to make it supply power at the necessary voltages. Particularly, as has been pointed out elsewhere in response to this question, it will have protective circuitry to prevent for example an overvoltage condition causing damage. This of course is not a guarantee, but it significantly betters the odds that a PSU malfunction or even a short circuit will not lead to further hardware damage.

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@mobilecomputing I'm not going to do your shopping research for you; that's not what Super User is for, and if you had asked for that in the question itself, it would most likely have been closed as asking for hardware recommendations is off-topic here. A server PSU is likely to be of reasonably high quality, but there is quite a bit of a difference between a PSU that can be installed in redundant position, and a high-quality PSU. Note that the ATX specification requires a certain degree of protective circuitry. –  Michael Kjörling May 28 at 12:59
    
The first two sentences in your comment... I could really do without. But you took time to write a thorough response , so that is my upvote to your answer. I don't know what motivated you to write all this. I'll assume it's all good intentions. –  mobile computing May 28 at 14:24
    
@mobilecomputing Providing lasting value to the community at large. –  Michael Kjörling May 28 at 21:01

Your PSU should be able to provide enough power to cope with the cumulative demand of all the components in your computer. If all the devices are working correctly and drawing the required power they need, providing your PSU is rated to the correct power and is working correctly, your devices should not be damaged majorly in the event of a power spike. This is what fuses and RCDs are for. You should, however, invest in a surge protector at least.

For power losses you could invest in a UPS as this will keep your devices on and gracefully shutdown the system in the event of a power cut. OR, keep the device on with enough power until power is resumed.

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A PSU also does line conditioning, so better power is sent to the PSU to be converted. –  AthomSfere May 28 at 11:40
    
This bugs me about this site. An answer is able to be downvoted without a reason... –  Big Chris May 28 at 11:54
    
@BigChris I don't like it either. Hope this vote restores balance. You at least answered my question and gave suggestions, so it deserves an upvote anyway. –  mobile computing May 28 at 12:12
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Lol cheers :) I wasn't having a moan, I just believe that if an answer isn't quite right, then whoever knows better should comment to improve. If I'm completely wrong then I'll even delete the answer. –  Big Chris May 28 at 12:14
    
I agree, I did not downvote but I left additional information for the sake of readers. It would be nice if more voters gave a reason for downvoting –  AthomSfere May 28 at 12:58

Ignoring the misunderstandings about power supply ratings for a moment...

Surge protectors and/or UPS's will help to isolate the PC from surges on the power line which might get coupled into the machine and cause trouble. (Most UPS units these days also provide surge protection.)

The odds of a power supply failing in such a way as to also take out the motherboard, WITHOUT a powerline surge, are actually pretty low. Not impossible, but I don't think the risk is anywhere near high enough to justify trying to add protection states between the PSU and the rest of the system. (Two regulators in series is not impossible, but increases cost and complexity and would require some power to operate, and if a surge manages to get to the machine it can blow two stages as easily as one.) Given that life-critical and business-critical equipment hasn't felt the need to do this, I don't think you can justify it.

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