What happens if the computer power supply does not meet the peak power of the host?

Assuming that the power consumption of a computer during light usage is 400W and the power supply is 500W, and during heavy usage, the peak power is 600W I do not fully understand the specific operating principle of the power supply, so I have made a possibly immature assumption

Insufficient Power for Peak Performance

Let’s start with the conclusion: If the peak power is not satisfied, the computer can usually start up, but it will black screen and restart as soon as the load increases.

The standby and low-load power consumption of a computer is actually lower than many people imagine. For example, the one I most commonly use, with an i9 9900KF and a 2070s, has been tested to have a power consumption of around 100W during daily standby, and about 300-400W under full load.

As you can see, the fluctuation range is quite large. I only mentioned the CPU and GPU because they are the two biggest power consumers.

Components such as the motherboard, cooling fans, hard drives, and memory have power consumption in the single digits, such as a few watts. Especially for solid-state drives, it can even be only a few hundred milliwatts. However, this doesn’t mean that they will all run at full capacity when the computer is turned on. They operate independently. For example, if an application is using the CPU, the power consumption may be pulled to around 200W by the CPU, but at this time, if the GPU is not being heavily loaded, the GPU’s power consumption may be low. But this doesn’t mean that as long as the total wattage is greater than what the CPU requires, everything will be fine. We can further discuss the details of power supply power.

Let’s take a power supply nameplate as an example to understand it practically. First, let’s take a look at the model which is labeled 550, but the rated power is only 450W. This kind of deceptive operation is not very common today, but it hasn’t disappeared, especially on low-priced power supplies. So, the number does not equal the power. That’s the first point.

Then, all power supplies have a nameplate to tell you the wattage they operate at. The basic function of a power supply is to convert the AC input of 220V to DC output with different voltages such as 3.3V, 5V, and 12V.

When looking at the nameplate, the first thing we can see is that a 450W power supply cannot directly provide 450W of power to a single component. Among them, +12V is used to power the most power-hungry CPUs and GPUs, so it has the highest wattage. But at the same time, we can also see that 396W is the sum of +12V1 and +12V2 (1712=204W for the graphics card, 1612=192W for the CPU). This is called a “dual-rail power supply.” There is no absolute good or bad for single-rail or dual-rail power supplies, but one disadvantage of dual-rail power supplies is that the upper limit of power allocated to the CPU and GPU is restricted. On this 450W power supply, the CPU can allocate a maximum of 192W, and the graphics card can allocate a maximum of 204W. So, even though 200W+100W seems to not exceed the total of 450W, if you have a graphics card that consumes exactly 200W, it will crash when you use it.

On the other hand, for a single-rail power supply, it is responsible for the CPU and GPU, so the CPU can share the maximum power of 420W. If a non-K CPU with a power consumption of around 100W at full load is used, it provides an additional 100W that can be evenly distributed to the graphics card compared to the dual-rail power supply mentioned above.

Therefore, currently, the better power supplies are single-rail designed, which is more mainstream. In most cases, choosing a single-rail power supply would be a better option. The reason why you see some entry-level power supplies using dual-rail is because after splitting the load, the load is not high. As a result, they can further reduce some specifications on certain components and save a little more power.

ATX3.0 Power Supply

I have encountered this issue before. After confirming that it was a power supply problem, I have always been purchasing Li Da bricks for power supply.

First, let’s talk about the symptoms: insufficient power supply leads to power loss and restarts

I don’t actually play games very often, but what kind of situation did I encounter? The computer I used:

  1. Some disks disappeared while in use.
  2. Sometimes the computer fails to boot and shuts down while waiting.

Why does this happen?

The power consumption of the disks is like this: the power consumption is very low during normal use, ranging from 2 to 5 watts. However, 3.5-inch hard disks have a characteristic that the power consumption is relatively high during startup, reaching an instantaneous power consumption of up to 30 watts. As a result, the hard disk fails to start and hangs.

Because I used to have multiple hard disks connected, when starting up, 4 to 6 hard disks need to be simultaneously started, and this power consumption can reach over 100 watts. Compared with the usual power consumption of less than 15 watts when all 6 disks are running, the difference is huge. If it exceeds 50 watts, it will cause problems.

So in 2015, I happened to upgrade and directly replaced it with a 750-watt power supply. However, my computer doesn’t even have a dedicated graphics card. Then, I also understood another fact: power supplies are not consumables. A good power supply can be used for ten years or even more. That power supply cost me around 400 yuan, and I sold it for over 200 yuan last year. After deducting the amount, I used it for more than 7 years and only spent a little over 100 yuan. Can you believe how happy I was?

I sold it because I switched to an ATX 3.0 power supply.

Now I have two power supplies: an 850-watt ATX 3.0 and a 1000-watt one. I’m not afraid of any graphics card with these.

So you don’t need to worry too much about peak power. Just go for the Li Da brick, because power supplies usually come with a minimum of 5 years warranty (as long as they are not unbranded). Therefore, if there are any issues during your lifetime, you can directly get a replacement or repair. But power supplies are usually not easy to repair, so they usually have to be replaced with new ones. And generally, a specific model is only kept for three to five years. Usually, they will directly give you the new model.

So I think power supplies should be worth the investment. Insufficient power supply and unstable voltage can potentially damage the motherboard, CPU, and even the graphics card. The cost of any of these components is higher than that of a power supply, so it’s not worth it.

ATX 3.0 Power Supply

For the current situation, I believe ATX 3.0 power supply should be the preferred choice. Its main advantage is that it can handle higher peak power consumption loads:

As you can see, ATX 3.0 power supplies can handle a peak power redundancy of 200% in 100μs (microseconds), which is a wider range compared to traditional power supplies.

Of course, for the current situation, we should choose a “true ATX 3.0” power supply, such as the one that comes with the standard PCI-E 5.0 power interface:

I personally use one with this feature, and it also includes the corresponding power cables. The advantage is that there is no need for adapters, and it is more convenient to insert the graphics card without obstructing the side panel of the case. It also provides better safety. There is nothing more to say about it. Anyway, the price difference is not significant.

Power Supply Protection Modes

Is the power supply awesome or not, an awesome power supply can withstand anything. Here, all the major brands' titanium gold fully modular power supplies can achieve this.

A slightly less-awesome computer will make a clicking sound when the relay disconnects the power. Then it will enter power protection mode and cannot be turned on. Power must be disconnected and reconnected to turn it on again. This will not damage the hardware. Most high-quality power supplies like Delta, SeaSonic, and FSP can achieve this.

An not-so-awesome power supply will continuously lower the output voltage of 12V until it reaches around 10.5V-10.8V, causing the whole machine to turn black and automatically restart. Repeating this process multiple times may damage the mechanical hard drive or dedicated graphics card. Specifically mentioning the pre-2010 half-bridge rectifying version of the Huntkey Coolking 400-watt power supply.

Power Supply Capacity and Overload Issues in PC Configurations

Simple answer: The most common symptom is unexpected power loss and system restart.

Detailed answer:

The situation may vary depending on the machine’s configuration and power supply, as well as occasional overload.

Here are a few examples:

For example, this machine I had many years ago:

X58 + overclocked i7 980x to 4.3GHz, with two famous electric tigers GTX480 in SLI. In theory, the power consumption of two overclocked GTX 480s at full load would already exceed 600W, plus the CPU and a bunch of other peripherals. It wouldn’t be a problem to exceed the rated power of 850W of the HX850 power supply. Moreover, the HX850 by Corsair is not the top of the line product at that time. There is also the AX series. However, I used this setup for a long time without any problems, and it was exceptionally stable.

A similar situation occurred a few years later:

This time, it was Titan X 4-Way SLI, with the power consumption of four cards exceeding 1000W, and the overclocked 5960X to 4.5GHz, definitely surpassing the rated power of the 1200W power supply. But no matter how I pushed it, this machine remained stable as ever.

So, based on my experience with these setups, I continued with extreme operations and eventually encountered unexpected issues:

Later, I had another machine with the following configuration:

6950X overclocked to 4.2GHz


2070 graphics card (overclocked)

8 mechanical hard drives


The power supply was SeaSonic’s 760XP2 as shown in the picture:

I didn’t specifically test the power consumption of this setup, but it definitely didn’t reach the rated power of 760W.

Later on, I got hold of a 2080Ti and replaced the 2070, and it worked normally as well.

After that, I switched my main machine to a 5950X, and the X299 + 7980XE from my previous main machine was moved to this new machine. The final configuration was 7980XE + 2080Ti + 64G DDR4 + 6 mechanical hard drives + 2 U.2 SSD.

I tested this setup on a regular power socket with the main machine. The power consumption was around 300W at idle and over 600W when running games like Cyberpunk 2077. Although the main machine used an HCP1200 power supply, I thought that the SeaSonic’s 760W 80 Plus Platinum would be sufficient.

However, whenever I ran a large 3D game, the machine would randomly shut down and restart. At first, I thought it was due to unstable overclocking, so I lowered the CPU frequency to 4GHz and returned the memory to default, but it still restarted. When I reduced the frequency of the graphics card to default, the CPU overclocking worked fine. Then, I suspected that the graphics card was problematic, so I brought over another 2080Ti from the main machine, but it still restarted. It stopped rebooting when I switched to the 1200W power supply from the main machine.

Alright, now it’s certain that the issue is related to the power supply. I thought the power supply was damaged, so I applied for a replacement. However, the new power supply still had the same problem. In the end, the conclusion was that even if the power consumption displayed on the socket was less than 700W when running games, the 750W rated power supply couldn’t handle it when the graphics card was overclocked.

So, I went straight to buying an HCP1300 for the main machine, and the previous HCP1200 was moved to the secondary machine, and the problem was solved smoothly.

So, to sum up the problem of a rated power supply of 500W and the system’s peak load of 600W:

If you’re lucky enough to have a power supply with lenient overload protection, you won’t notice any anomalies. However, power supplies with lenient overload protection fall into two categories: one is where manufacturers invest heavily in materials, like the HCP1200, which can withstand stable voltages even when overloaded to 1600W, and the other is power supplies made with shortcuts, where overload protection is virtually nonexistent, and they may be able to endure short-term overloads but will blow up if subjected to long-term overloads.

If you’re unlucky enough to have a power supply with strict overload protection, like the SeaSonic’s 760XP2, even if your computer’s long-term full load power consumption is below the rated power of the power supply, the power supply will automatically restart due to overload protection as soon as there is a sudden increase in power.

Especially in recent years, graphics cards often have a labeled TGP that appears low, but during heavy loads, the instantaneous peak power consumption can often exceed the TGP by a significant margin. For example, the labeled TGP for the 2080Ti is 250W, but the peak power consumption is 402W/0.1ms. If you overclock it further, it’s common to see instantaneous power consumption exceeding 600W.

In this case, a sensible approach would be to calculate the current based on your own configuration and check whether the peak current of the graphics card + CPU’s 12V power supply falls within the range that the power supply can handle. However, executing this sensible approach is difficult in practice, and you can only rely on tests conducted by others. But these kinds of extreme tests usually don’t appear until a long time after the product’s launch.

So, my principle for buying power supplies now is to calculate the rated power of the power supply as double the labeled full load power consumption. This simple and crude method is definitely not scientific, and it may even seem wasteful. However, at least this method guarantees that the power supply’s power will be sufficient, saving you the trouble of further experimentation.

Power supply instability and frequent system crashes and restarts

It is possible to experience blue screen or restart, as well as freezing and crashing. The power supply is crucial, while other components can be economized. The quality of the power supply directly impacts the stability of the computer’s operation.

Previously, I used an x79+e52666 motherboard, a GTX760 graphics card, 4x8GB third-generation ECC memory, 120GB solid-state drive, and 4 mechanical hard drives. The power supply was a XinGu rated at 500 watts.

I calculated that the power supply was sufficient. However, there was one time when I was playing GTA5 and the computer restarted. I thought it was due to high temperature since the graphics card was under full load and generated a significant amount of heat. The GTX760 was a Dell OEM version with a very noisy turbo fan.

At the time, I didn’t pay much attention to the computer restart, thinking it was caused by overheating of the graphics card. I didn’t play GTA5 often, usually, I played online games like CF or LOL, which are less demanding on the graphics card.

Later, the computer started frequently disconnecting from the hard drives, sometimes not recognizing them. However, a restart would fix the issue. I thought it was due to a faulty hard drive since all the hard drives were salvaged from an old computer. I even replaced a few hard drives, but the issue persisted. It wasn’t sudden but rather occurred from time to time. There was one instance when I was copying files, and it suddenly interrupted.

I turned off the computer, reconnected the power supply cables to the hard drives, and changed the SATA cable. It worked fine for a while, but the problem resurfaced. I started suspecting that it was a problem with the X79 motherboard since it was a knockoff brand. So, I replaced it with a Huanan motherboard. Huanan is a major player in the knockoff motherboard market.

Initially, everything seemed fine after the replacement. However, after a few days, the issue arose again. So, I replaced the Xingu 500-watt power supply with a 500-watt power supply from Great Wall, and I haven’t encountered any of the aforementioned problems since then.

Although the Xingu power supply was clearly labeled as 500 watts, it was not stable under high load. Furthermore, when multiple mechanical hard drives were connected, they would occasionally disconnect. This is the result of the power supply not meeting the peak power requirement of the system.

I had sold a few Xingu power supplies before and never encountered this situation. It might be due to the fact that I used salvaged power supplies. Back then, I thought it was unnecessary to buy a new power supply as the motherboard itself was a knockoff. Consequently, except for the case, all other components were second-hand, and as a result, issues arose.

Based on my estimation, either the power supply was falsely labeled or it had aged and deteriorated over time. Before using this X79 motherboard, I had used an H55 motherboard with an i5 760 processor for some time. I even overclocked it, as the default frequency was 2.8GHz but I managed to overclock it to 4.2GHz. I used it for about a year before the motherboard failed.

LGA1156 motherboards are not easy to find, and buying second-hand ones can be risky. That’s why I decided to try the X79 motherboard. Initially, I never thought about replacing the power supply since I believed that as long as it could provide power, it should work fine. I didn’t anticipate the continuous problems later on, such as frequent restarts and blue screens. The restarts are likely caused by unstable voltage, while the blue screen may be the result of unstable power supply during the hard drive read process.

Power supply: importance and considerations

The peak power of the power supply is not enough, black screen restart is unavoidable, and it is very likely to give you a BOOM with a lousy power supply.

Back in the day, I was also a naive beginner. I was deceived by an inferior computer technician at the computer store and spent 4,000 yuan on a computer host that cost less than 2,800 yuan. Faced with ignorant consumers, the cunning salesman dared to use a butcher’s knife, but at least he taught me a saying: “Don’t skimp on the power supply”. So, the power supply of this computer was really well-made, but the motherboard and memory gave me a big headache.

Why is the power supply so important for a computer? You can think of it as the heart of a computer. If the heart is weak, it will not be able to supply enough blood and cannot withstand intense activities. It can handle regular jogging, but if you suddenly sprint for 100 meters, you will faint and go into shock. The same goes for a computer host. Even if you use a low-quality power supply for your computer, it can handle everyday tasks like writing documents, making presentations, and playing minesweeper for about two years without any problems. However, if the rated power of the power supply differs significantly from the “passing threshold” and the computer performs high-load tasks for a prolonged period of time, the power supply is guaranteed to fail. Black screen restart is the most basic problem, and if you’re unlucky, it may expose its true nature as a “time bomb” and explode.

Nowadays, I can assemble a computer without being tricked by salesmen and I pay more attention to the power supply configuration of a new computer. Power, efficiency, structure, interfaces, modules, materials, workmanship, and other aspects all need to be carefully considered. As for the question of the peak power of the power supply that was asked by netizens, just remember that the total power should be higher than the peak power consumption of the entire PC, leaving 100-150W of redundancy. Otherwise, troubleshooting black screen restart or various forms of malfunction will only add to your troubles.

The specific amount of redundancy generally depends on the quality of the power supply. If you buy a regular brand power supply, you can multiply the rated power of the major hardware components by 1.3, or add 100-150 watts to the total power, which is roughly a reasonable power supply power. For example, let’s say your computer has a total power consumption of 400W, then the power supply should have a rated power of at least 400x1.3 = 520 (or 400+100 = 500), which is 550W.

If you choose a high-end power supply from a well-known manufacturer, you don’t have to be so strict (note that it’s not an entry-level power supply, as even well-known manufacturers have pitfalls in their entry-level power supplies). Adding 100 watts to the total power is also acceptable. But still, don’t skimp on the power supply. If your budget allows, try not to be stingy. For example, if the reasonable power is 600W, it’s more reliable to choose a power supply of 650W or higher.

From the end of last year to this year, many netizens who were building a new computer would prioritize the 40-series graphics card. In that case, the new ATX3.0 standard is the better choice. If you don’t need the new configuration for the time being, when upgrading an old computer, you can choose a power supply strategy that is above the threshold of “one step ahead” so that it can continue to serve you well when you later switch to a new graphics card.

Power Supply: ATX3.0 vs. High Power Rating

When the computer is used lightly, the overall power consumption will not be so high. Most computers for daily office use consume less than 100W, and 400W is definitely beyond the range of light usage.

What happens when it reaches peak power consumption depends on the OPP protection of the power supply, which is essentially the amount of margin left to deal with sudden overload. Good power supplies can handle a 20% or even 25% overload, while some ordinary power supplies may trigger protection at just 10% overload. Poor quality power supplies may not even reach their nominal power before encountering problems.

Nowadays, ATX3.0 power supplies are gradually becoming popular, and one very important improvement in the 3.0 specification is the instantaneous load capacity.

Increased tolerance for high power spikes, for the compatible PSU platforms. Up to 200% of the PSU’s rated power for 100μs with a 10% duty cycle.

The peak power consumption of the 30 series and 6000 series high-end graphics cards in the past has caused a considerable number of black screen restart issues. As a result, many power supply brands have emphasized and promoted this in the details of their new products. The new standard is obviously more stringent, leading directly to price increases.

If you are using a power supply certified by ATX3.0, this instantaneous power consumption is not a concern and users will not notice any difference. If it is an old standard power supply, it depends on how much margin the manufacturer has left. If the margin is insufficient, the power supply may not be able to handle it and will trigger protection, resulting in a direct power outage or voltage drop that causes the hardware to operate under undervoltage conditions. In any case, it will have a significant negative impact on the lifespan of the host computer.

Therefore, there are two approaches to choosing a power supply. One is to calculate based on the nominal power and then choose an ATX3.0 power supply where the instantaneous power consumption is irrelevant. The other is to choose a high-power old standard power supply, such as 1000W, where even if the instantaneous power consumption surges, it will still be within the design range. As for gold and silver ratings, they are used to measure efficiency and have no relation to the power supply’s overload capacity.

High School Physics Teacher’s Responsible Knowledge: The Power Consumption During Computer Start Up and Overpower Protection.

Cold knowledge of getting cold unexpectedly: The BIOS does not have a power control program, so during the self-check, all components of the computer operate at maximum power until the buzzer beeps short “drip” sound, indicating self-check completion.

It’s not in the textbook, nor does it appear in exams, but responsible high school physics teachers would mention this cool knowledge: The current of an electric motor at the moment of starting can be several times its rated current. DIYers don’t mention it because the power supply has a peak power that is at least 20% higher than the rated power. Generally, this momentary power can be handled by the peak power of the power supply.

Due to the above two points, the power consumed during the computer’s self-check is much higher than the power used during normal operation. The peak power of the power supply must be greater than this startup power.

Therefore, the power supply designed by the OP will trigger the power supply’s over-power protection during the self-check phase and will endlessly cycle between “self-check-over-power protection-motherboard power loss shutdown”, not leaving any chance for the OP to troubleshoot.

Efficiency and Peak Power

If your power supply is good, achieving gold or even platinum efficiency, it is designed with redundancy to handle occasional overload usage. In this case, there is no problem, although efficiency may decrease.

However, if your power supply is average, under normal circumstances, it may cause a black screen and restart if it cannot meet the peak power consumption of the host.

The Impact of Insufficient Power Supply for Computers

Which computer components consume power?

Tips for selecting a power supply

Is a higher power supply better? In the past, I enjoyed tinkering with digital computers. I liked buying second-hand computers and modifying them myself because I didn’t want to waste money since I earned it hard, but I couldn’t let go of my love for computers and digital technology. After buying a computer, I encountered a problem. The computer would suddenly shut down while playing games or writing, and even the repair shop couldn’t find any problems. Finally, I surprisingly thought of the power supply as the culprit.

Because the computer I bought was second-hand, I considered that the power supply might be trash, so I spent over 600 yuan and bought a new power supply. After that, I never encountered the same problem again. So, it is true that choosing a good power supply for computers is really important.

  1. What happens if the computer power supply does not meet the peak power of the computer?

What else can happen? Of course, there will be protests. The computer will frequently black out and restart, work under high load, accelerate the aging of electronic components, and reduce the lifespan of the power supply. The power supply for the original poster’s computer has a power of 500W, which is definitely not enough under heavy loads.

  1. Determine which hardware consumes power

The CPU, hard drive, graphics card, motherboard, and other hardware of a desktop computer all need power supply support. The power of the power supply mainly depends on the power of all the computer’s hardware, and then expands it by 100-300W, aiming to bear the computer’s peak power, such as the moment the hard drive starts up and the graphics card under heavy load, which are all power-hungry because they need to be powered. If there is not enough power, they will not run perfectly, which is very damaging to the hard drive.

The major power consumers of a desktop computer are the CPU and graphics card. As long as you have these two parameters, you can determine the appropriate power supply wattage. The power consumption of the motherboard, memory, and hard drive is relatively low. 50W should be enough. Mainstream CPUs are usually around 80W, while high-end ones may reach 100W. Entry-level graphics cards are around 100W, advanced ones are around 150W, and high-end ones are around 180W.

The power consumption of hardware is: CPU 80W + graphics card 150W + other hardware 50W + 100W~200W = 380W~580W

  1. How to choose a power supply

Now that you know the power of the computer power supply, you can determine the size of the power supply you need.

Personally, I prefer power supply manufacturers with accumulated industry reputation. Good quality brands include Huntkey, Great Wall, Antec, Patriot, and Jinhetai. I remember that the power supply I bought was from Jinhetai, and I used it with peace of mind.

As for power supply types, the current mainstream types are ATX and SSI. ATX power supplies are dedicated to household and office use. If the load is larger and stability is better, you can use SSI, which is specifically designed for servers and workstations.

  1. Is a higher wattage power supply better?

In my opinion, it is best to use one that is within a reasonable and applicable range. After all, good power supplies with higher wattages also come at a higher price. The user experience is naturally great, but for ordinary players, it is sufficient. So, there is no need to consider a power supply that is too large. A 600W power supply is almost enough.

I am @HomeApplianceMaster, specializing in smart home appliances/digital technology. If you have any other questions, please feel free to leave a comment, and I will reply as soon as I see it.