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ATX 3.0 PSUs Explained - Will You Need One?

ATX 3.0 or the ATX Version 3.0 Multi-Rail Power Supply Design Guide is the new PSU standard heading our way. But who will need it and why?


ATX 3.0 PSUs Explained - Will You Need One


The old saying "if it ain't broke, don't fix it" could well have been the tagline for power supply units, which haven't had a refresh in design spec for 20 years. Whilst manufacturers have certainly been making changes to their own product lines since 2003, making them silent running and getting the best out of energy efficiencies, the new guide issued by Intel is focused on increasing efficiency and reliability even further.

In this article


What is an ATX 3.0 PSU?

The ATX Version 3.0 Multi-Rail Power Supply Design Guide from Intel will enable builders to get the most out of the next-generation technology we're hearing about - from the NVIDIA RTX 4000 series to a deep learning PC build with immense power requirements. Even the AMD RX 7000 series are being watched closely to see how their TDP compares to the titanic new NVIDIA GPUs, so clearly, power requirements are showing signs of increasing beyond the limitations of current PSU technology, certainly in the mid-tier price bracket at least.

RTX 40 Series Register Interest and Pre-Order Information

LATEST: RTX 40 Series Announced: Check out our RTX 40 Series Mega Guide

That said, the RTX 3080 has even been known to dial up the clock when it comes to power spikes, with a transient high of 533W recorded by Gamers Nexus, playing Doom Eternal in 4K resolution and Ray Tracing enabled. Although the spike lasted a mere 100 microseconds (100μs), that is more than enough to shut down an incapable power supply unit, the GPU, or cause any number of failures on the motherboard. Most modern PSUs from reputable manufacturers are designed to handle power spikes like these, which can be sustained for longer than 100μs in many cases.


GPU Power Excursions RTX 3080 and RTX 3090 Ti


Of course, the RTX 3090 Ti is the hungriest of all the power munching GPUs right now, with recorded spikes of up to 664W, giving us a great idea of what the RTX 40-series will bring. Considering everyone and their cousin believe the RTX 3090 performance is going to seem like an old GTX 260 in comparison to the next-gen NVIDIA cards, it will be fun to see actual benchmarks come release day.

The ATX 3.0 guide, however, addresses rare issues like these power spikes, and more besides, with "power excursions" ensuring GPUs don't crash. Finalised in February 2022, the new power supply standard supports the new 16-pin 12VHPWR power connector, enabling gamers and enthusiasts to pull 600W of power from a single cable.

There's also increased efficiency at idle, with Alternative Low Power Modes (ALPM) allowing for lower power consumption, which is an efficiency most manufacturers have mastered in the current generation, with the Corsair CX550F RGB being a good example. Alternative Sleep Mode (ASM), seen in be quiet! PSUs for example, will be replaced by ALPM and ATX 3.0.

Will you need an ATX 3.0 PSU?

With higher efficiencies and features designed for those who might experience power spikes (gamers, creators, deep learning data scientists etc.), and ATX 3.0 power supply is a standard you should set for your system. It is highly recommended that you upgrade your power supply if you are buying a new graphics card from the GeForce RTX 40-series line-up, though it remains to be seen what the benchmarks officially reveal for the Daddy of them all - the RTX 4090. An ATX 3.0 PSU may even be a compulsory purchase for this graphics card.

ATX 3.0 specifications

Here's what to expect from the new ATX 3.0 standard: -

  • Up to 3x GPU Power Excursion
  • New 12VHPWR connector to up to 600W
  • 12V rail can ramp to 12.2V allowing for lower voltage drops
  • 2.5 - 5x times higher slew rates for transient loads on the +12V rail (the rate at which the output voltage and output current changes)
  • PSU signals power capabilities to PCIe to enable power limitations on components such as GPUs and SSDs
  • Minimum of 175,200 power cycles
  • Greater than 60% efficiency for 10W load (or 2% of max-rated capacity and above 70% efficiency).
  • Rated for up to 200% of rated power for 100μs (with a 10% duty cycle).
  • Faster system wake up & Power On signal
  • ALPM to replace ASM


World's first ATX 3.0 power supply


Worlds first ATX 3.0 power supply from MSI


The MSI MEG Ai1300P PCIE5 is the world's first ATX 3.0 PSU, conforming to all Intel's standards, and providing us with a benchmark that shows the technology is easy enough to slot into current manufacturer tooling.

MSI, of course, have tagged on a bunch of features that are going to resound with the people that need the new standard the most. In MSI's own words, the MEG Ai1300P Gaming Intelligence feature " dedicated to providing many unique and useful features to improve the gamer's experience.".

This "Gaming Intelligence" MSI speaks of is in fact a user experience dashboard that will help optimise power when at full tilt. A mini-USB cable enables you to sync with the power supply unit and tweak power as required. In the MSI Center, you will be able to monitor the real-time status of the percentage of power supply to GPU and CPU as well as the total system wattage used. Great news for overclockers or anyone who bought Crysis 3 in the Steam Summer Sale in 2021.

Further into the specs, we see that MSI has highlighted Performance Mode, where the power supply turns on zero RPM functionality where the system has under 40% TDP, a nod towards the efficiency taglines and energy saving - as well as offering silent operation.

Most notably, the Multi/Single Rail Switch is the feature that sets this inaugural ATX 3.0 PSU apart - enabling the system to switch between single and multi-rail dependent on your actual needs. For creators and high-end gaming, this is a very interesting prospect. Even though multi-rail PSUs are not a new concept, having this feature with such an already highly efficient standard means significant gains overall.


Multi and Single Rail Switch

What are the latest ATX 3.0 PSUs?

The MSI MPG A850G PCIe5 850W Modular 80+ Gold PSU and ASUS ROG Loki 750W Modular 80+ Platinum PSU are two of the latest ATX 3.0 power supplies, and offer incredibly good power management, along with a raft of next-gen features. The latter, the ASUS ROG Loki, also offers 80+ Platinum efficiency, which is perfect for a build focused on energy saving.


MSI MPG A850G PCIe5 850W Modular 80+ Gold PSU

MSI MPG A850G PCIe5 850W Modular 80+ Gold PSU

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  • ATX Form Factor
  • Fully Modular
  • 2 x 4+4-Pin EPS CPU
  • 6 x 6+2-Pin PCIe
  • 1 x 12+4-Pin 12VHPVR
  • 8 x SATA
CCL Code: PSU2116|
Part Number: MPG A850G PCIe5
|Manufacturer: MSI


ASUS ROG Loki 750W Modular 80+ Platinum PSU

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ASUS ROG Loki 750W Modular 80+ Platinum PSU
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ASUS ROG Loki 750W Modular 80+ Platinum PSU

£25 Cashback from ASUS + Save 5% when you buy 3 or more eligible different items*
  • SFX-L Form Factor
  • Fully Modular
  • 2 x 4+4-Pin EPS CPU
  • 3 x 6+2-Pin PCIe
  • 1 x 12+4-Pin 12VHPVR
  • 6 x SATA

Price with £25 cashback:

£145.99 inc VAT

£170.99 before cashback

CCL Code: PSU2112|
Part Number: 90YE00N4-B0NA00
|Manufacturer: ASUS


The ATX 3.0 certification problem

The burning question, no doubt, for PSU manufacturers the world over, is how they can convert current SKUs to the new standard with the minimum of effort. There will be hundreds of thousands of current generation power supply units ready to go on the production line, so vendors will be eager to find out how they can fit the new specifications without it costing the earth (or passing costs on to consumers). Adding an ATX 3.0 version to an already popular line of PSUs would be the ideal scenario - but is it possible?

Under the ATX 3.0 guidelines, PSUs that use the PCIe 5.0 12VHPWR connector need to handle up to 200% of their rated power for at least 100μs (microseconds), 180% for 1μs, 160% for 10μs, and 120% for 100μs. These transient loads or power excursions as they are known are predominantly anticipated by next generation GPUs.

A lot of controversy currently surrounds the fact that manufacturers could label power supply units as ATX 3.0 ready, even without the PCIe 5.0 connector. How is this possible?

It all comes down to a table shared by Hardware Busters, which shows the power excursion requirements below or equal to 450W.



Power Excursion ratings


With this table in mind, Intel also states in paragraph of their guide that PSUs with more than 450W capacity must have a 12VHPWR connector. But manufacturers will also have noticed that they could produce an 800W PSU without a PCIe 5.0 12VHPWR connector, as this table shows - "...& PSUs without 12VHPWR Connector". There is no capacity stated, just "PSUs" without the connector. This essentially means that you could purchase an ATX 3.0 ready PSU that has only met the <450W requirements, and not the stringent tests required for 200% power excursions.

It is troublesome, then, that a vendor might produce an ATX 3.0 ready power supply unit for a new generation (read: very demanding) graphics card, and not future-proof it with PCIe 5.0, however. Yes, They could make a few minor adjustments for ALPM and ship some current-gen stock with new labelling - but that is where consumers might be severely let down.

Hot Hardware's TLDR said it all: "PSUs with over 450W capacity can be ATX 3.0 compatible, even without a 12VHPWR connector."

If you're buying a next-gen graphics card, then make sure you look for an ATX 3.0 PSU that clearly states it includes a 12VHPWR connector.

ATX 3.0 release date

ATX 3.0 power supply units will be shipping throughout the latter part of 2022 in time for NVIDIA and AMD graphics cards, and other products that will benefit massively the new PSU standard.