Is 850W Power Supply/PSU Overkill?

Building your first PC? Ensuring that it’s properly powered is one of the most crucial tasks you need to pull off. 850W power supplies are pretty common, it tends to be on the larger side, and it’s good for many builds.

Having an overkill power supply actually isn’t a bad thing, well except for the extra cost. If the power supply is larger than your system actually needs, it means your PC will only draw what it needs. You will also have extra room for upgrades which is a good thing.

But The worry of underpowering your PC is real, if you’ve ever done it before, the effects can be detrimental. Underpowered PCs will usually have slow performance, poor gaming performance, and stability issues.

But I can tell you 850W is not overkill, but it’s close to being overkill. Components such as graphics cards are becoming super power hungry, so 850W is often great for high end builds.

Is An 850W Power Supply Overkill?

power supply
Power Supply

The graphics card and the CPU are the most power hungry components, together they can consume a lot of power.

But 850W of power is a lot, it will take a power hungry CPU and GPU to saturate the entire power supply, so it can be perceived as overkill by many.

So yes, to most people, 850W is well in excess of what they need, so 850W can be considered overkill.

Also Read: Best 850W Power Supply

Is 850W Overkill For Gaming PCs?

A high end PC builder would tell you no, an 850W power supply is a perfect amount for a gaming build using a GPU such as the RTX 3090, or 3090 TI.

But the majority of PC builders don’t go for overkill builds, they typically stay within the range of something like an RT 3060.

In this case, then an 850W power supply can be perceived as overkill as 850 watts is excessive for the RTX 3060.

Graphics CardRecommended Power Supply
RTX 3090 TI(SLI)1200W(80+ Platinum)+
RTX 3090(SLI)1200W(80+ Platinum)+
RTX 3090 TI850W – 1000W (80+ Gold)+
RTX 3090850W – 1000W (80+ Gold)+
RTX 3080 TI750W – 1000W
RTX 3080750W
RX 6900 XT700W

The recommended power supply for the RTX 3090 and 3090 TI is an 850W power supply, and a 1000W power supply if you want to be safe.

But if you pick up a high quality platinum 80+ rated 850W power supply, you likely won’t need to worry about powering an RTX 3090 TI.

Is An 850W Power Supply Overkill For Video Editing?

For video editing, the main component is the CPU which means you won’t need a power hungry graphics card like the RTX 3090.

So for most video editing builds, an 850W PSU is definitely overkill as CPUs don’t consume as much power as GPUs.

However, CPUs can get power-hungry, especially with overclocking as clock speeds can exponentially increase the power usage.

This is why Intel CPUs will consume more power than Ryzen CPUs because Intel pushes hits 5GHz whereas Ryzen stays between 4 and 5 GHz.

CPU GenerationRecommended Power Supply
Intel 12th Gen700W
Ryzen 5000th Series700W
Intel 11th Gen700W
Ryzen 3000th Series550W
Intel 10th Gen550W

So if you have a PC that is Intel 12th gen, or Ryzen 5000th gen based, and you don’t use a power hungry GPU, you can get away with a 700W PSU.

However, Intel 13th gen chips are expected to run hot, be power-hungry, and be crammed with a load of cores, so you will most likely need at least an 850W power supply.

This is because an Intel 13th gen chip is expected to have around 24 cores, and run as fast as 5.8GHz.

And if you look at this graph, after the clock speeds pass 4 GHz, the power consumption increases exponentially, so you can expect the I9 13900K to consume an unheard amount of power.

What Increases A Computer’s Power Requirements?

All components connected to the PC which includes peripherals will consume power, but you should always focus your attention on the CPU and the GPU.

The RAM, SSD, HDD, and Fans will probably consume a maximum of 50W, so their power consumption is negligible

A CPU on its own can consume up to 150W of power, and a single GPU can consume up to 450W of power, so you need to calculate your needs carefully.

Factors That Increase Power Requirements:

  • All Components
  • Clock Speeds
  • Overclocks
  • Fan Speeds

How To Know If You Need An 850W Power Supply?

To find out what power supply you need, you can use an online power supply calculator, which will calculate the consumption of all the components you pick.

As recommended, you will need between an 800W and a 900W power supply if you’re going to be running an RTX 3090 TI + an I9 13900K.

Newegg Calculator RTX 3090 TI + I9 13900K power requirements

You can even use PCPARTPICKER to calculate the best power supply for your PC, and it’s helpful because it adds up all the costs.

Top right it displays the estimated wattage the system will need, you should always add on an extra 50-100W when using PCPARTPICKERS power supply calculator.

PCPARTPICKER PSU Calculator – RTX 3090 TI + I9 12900K

Is TDP Accurate For Power Consumption?

TDP stands for Thermal Design Power, and it’s measured in watts. TDP is meant to measure the maximum power consumption a chip will consume under max load.

So if a chip has a TDP of 150W, it may consume 150 watts under full load, it’s like an operational ceiling for chips under factory conditions.

TDP does not accurately measure the amount of watts a CPU or GPU will consume under typical conditions as power consumption is lower than TDP under lower loads.

It’s incorrect to look at TDP as the same as power draw, if a component had a TDP of 850W, it won’t draw 850W 100% of the time.

Is Having An Overkill 850W Power Supply Bad?

If you have bought an 850W power supply when your computer doesn’t need it, then it’s not necessarily a bad thing in terms of how the computer performs.

Your computer will only draw what power it needs, it will never draw the full 850W as that could damage the components.

But you could obviously save money going for a power supply with less wattage, and save the money for a better GPU or CPU.

There is one benefit having a huge power supply gives and that’s upgradability. If you intend on upgrading your computer in the future, you won’t have to upgrade the PSU.

What Brands Make The Best 850W Power Supplies?

Looking for a decent power supply is a task everyone should do, never cheap out on a PSU as it can cause significant damage to your components.

Corsair – Is a decent power supply brand that sells some high quality PSUs. The Corsair RM850x (2021) is one of the best 850W PSUs from Corsair.

EVGA – Is also another reputable brand in the power supply market, they have some popular units such as the EVGA SuperNOVA 850 P2.

Seasonic – Have some high quality power supplies, they’re great if you’re looking for something durable like the Seasonic FOCUS Plus 850 Platinum.

Quick note – Always pick a power supply that has a decently long warranty like 10 years!

So When Do You Need 850 Watts Of Power?

With everything being said, an 850W power supply is perfect for something looking to build a high end PC with components like the RTX 3090 TI.

You won’t need an 850W power supply if you’re mid-range gamer, you can do fine with a 600-700W power supply.

But if you’re looking to be future-proof, then there’s no reason not to go for an 850W power supply, it will be great for high end GPUs in the future.


Yes, 850W power supplies are overkill for the majority of people, but there are some realistic uses such as building a high end gaming machine.

Also Read: Is 1200W PSU Overkill

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