What is an ATX 3.x / PCIe 5.x Power Supply Unit (PSU)?

We sell ATX 3.x / PCIe 5.x compliant PSUs, but also ones that don't meet these specifications: so, what's the difference, and when do you want/need the latest PSU technologies?

Power supply history, and how we got here

Although we never named them as such, all the PSUs that we've been using have been ATX 2.0 or above since we began business in 2013. Each year, we've seen PCs get more capable every year; providing insanely fast data access and performance in the most intensive tasks for things we would have been called crazy for imagining back in 2013. These advancements have made PCs quite demanding in terms of their power requirements, and we don't mean simply in the amount of power, but also how it's delivered.

ATX 2.x

With ATX 2.0 being introduced in the early 2000s, this whole generation of ATX relied on 6 or 8-pin connectors that were rated for 75w and 150w respectively. Evidently, for many years this was adequate, but with the recent advances in GPU technology it was clear that changes were needed and would be beneficial.

With this in mind, Intel announced the ATX 3.0 specifications in 2022. Designed to ensure that even the most powerful GPUs would safely and efficiently receive all the power they need.

What does ATX 3.0 deliver?

More reliability, better efficiency (including at idle load levels), and the ability to provide graphics cards with up to 600w of power.

PCIe 5.0 12VHPWR connector

Perhaps most importantly, it brings us the 12VHPWR connector which features 12 pins for power delivery instead of 6 or 8 as the case was previously. There are an additional 4 data pins on the connector which allows the PSU to communicate with the GPU. The 16-pin PCIe 5.0 connector enables PSUs to supply up to 600w while maintaining excellent efficiency and reliability. To be clear though, not ever ATX 3.0 / PCIe 5.0 compliant PSU will be able to supply 600w to the GPU. While 12VHPWR can supply up to 600w, there are also 450w, 300w, and 150w connectors which would be present on lower powered PSUs, bringing the improved features to any GPU utilising the new connector.

The additional beauty of the data pins, based on information that Intel has provided, is that in scenarios where a graphics card is not being provided with enough power, the graphics card driver would alert you about it and let you know the GPU is running in power-limited mode. As it stands today, we're led to believe that the system would simply not boot and would display an error message about the issue.

Aren't the adapter/converter/dongles just as good?

While they may get the job done, Intel and the ATX 3.x standard do not sanction them, although they're not expressly forbidden either. The existing PSUs with their 8-pin power connectors should provide a maximum of 150w, as previously mentioned, but in reality, most PSUs have apparently been able to support 324w (27 amps @ 12 volts) or even 468w (39 amps @ 12 volts) according to Corsair. The issue being that there's no guarantee or clarity for the 8-pin cables.

Power excursions

Next on the list of important changes is ensuring safe power excursions. A power excursion is an event that can occur with hardware, such as a GPU, momentarily drawing more than the normal power it's meant to operate at. With Nvidia's RTX 40 series, power spikes of up to 1800w (or 3 times their rated power) have been logged. ATX 3.0 specifies that PSUs can briefly output 2x of their total power (compared to ATX 2.0's 1.3x), and 3x of the GPU's rated power - which is why the data pins are important!

While it might sound that power excursions are an anomaly that shouldn't occur in the first place, it's apparently the case that limiting the extremely short-lived excursions would also mean limiting the higher-end of GPU performance. So, with this PSU innovation we can have more powerful & capable GPUs.

There were quite a few reports of those with RTX 3080s and 3080 Ti GPUs crashing systems with "transient voltage spikes" pinned for the cause. By outlining what is to be tolerated by power supplies, graphics card manufacturers can equally ensure they stay within the power limits to make these crashes a thing of the past - without sacrificing the performance to get there.

What does the latest ATX 3.1 / PCIe 5.1 deliver?

ATX 3.1 specifications provide some useful updates to the previous 3.0 specification which is especially important for high-end GPUs and components.

Hold-up...

Firstly, there's the shorter hold-up time: Measured in milliseconds, hold-up time indicates how long a PSU can sustain its output within specified voltage limits after a loss or drop in input power. ATX 3.1 features a shorter hold-up time of 12ms, compared to ATX 3.0's 17ms hold-up time. This results in a small improvement in the PSU's efficiency.

12V-2x6 Connector

As you may have seen/heard about in plenty of coverage of the ATX 3.0's original 12VHPWR connector, there were some dramas that unfolded due to some design short-comings, even though we here at Evatech never encountered the issues covered. Making amends on the flaws nonetheless, the new 12V-2x6 connector is designed with longer conductor terminals (12V and ground) for improved conductivity, as well as shorter sense pins.

The shorter sense pins allow your GPU to now shut off if the connection comes loose. With that being said, 12V-2x6 connector is a welcome update as it addresses the primary issue with the 12VHPWR connector where users were experiencing failures.

The 12V-2x6 connector is still capable of relaying up to 600W of power, accommodating the most demanding GPUs and components.

In summary, ATX 3.1 delivers some key improvements as compared to its predecessor. They might seem minor, but it's a better standard, so it's a worthwhile improvement if you're getting a new PSU anyway.

Availability of ATX 3.0 / PCIe 5.0 vs ATX 3.1 / PCIe 5.1

While most of the PSU brands & models that we regularly work with have now made the switch to the slightly upgraded 3.1/5.1 specifications, there may still be some slightly older stock out there with our suppliers, so for the time being we'll continue to promise ATX 3.0 / PCIe 5.0 at minimum, and while in all likelihood you would receive a 3.1 / 5.1 unit, we can't yet make that guarantee. If you need further clarity, please contact us prior to making an order for more info.

Do you need an ATX 3.x PSU?

If you have a scenario that isn't covered above, feel free to ask for our input!

In addition to above, anyone who is after what should be an extremely reliable, robust, efficient, & future-proofed PSU in their system may benefit from the latest in PSU technologies.

To date, out of the hundreds of ATX 3.x / PCIe 5.x PSUs that we've put out into customers hands, and also our pre-built & custom PCs: not one has come back as faulty yet. So, we're off to a great start to this new era in power supplies!