With ATX 3.0, Intel has presented the first major revision of the power supply specification since 2003, which should lead to more reliability, better energy efficiency and an additional power supply for graphics cards with up to 600 watts.
Under the name ATX Version 3.0 Multi-Rail Power Supply Design Guide, Intel, in cooperation with other leading PC and hardware manufacturers, is presenting what is probably the most comprehensive update for the ATX power supply standard. Key improvements include a 12-pin PCIe connector for extremely power-hungry graphics cards, new seals for power efficiency, power supply noise and form factor, and increased idle efficiency.
12-pin connector for graphics cards becomes the standard
The striking new feature of ATX 3.0 is the “PCI-Express 5.0 12VHPWR” connector. The connector features 12 pins instead of the usual 6 or 8, with a very similar (but smaller) design per pin. There are also features that include a smaller connector that carries additional signals that tell the graphics card how much current the power supply can currently deliver.
Currently, adding power to the graphics card depends on how many 6- or 8-pin connectors you can plug in, with 6-pin rated at 75 watts and 8-pin rated at 150 watts. With the new PCIe 5.0 connection, the power supply and cable can deliver between 150 and 600 watts, depending on the model.
Nvidia’s GeForce RTX 3090 Ti was the first GPU with a PCIe 5.0 connector, but since there are still no power supplies with a PCIe 5.0 connector, the graphics card manufacturers included adapter cables or dongles that allow three 8-pin to one 12-pin connection united. They work in practice, but are outside of the current ATX specification.
Reading tip: PCI Express 5.0 with new connectors up to 600 watts
While the included adapters are fine, what you connect them to does matter. Technically, 8-pin connectors support a maximum of 150 watts – so that’s a total of 450 watts if you use three of them. In reality, according to the Corsair manufacturer, most power supplies and most 8-pin connectors support 324 watts (27 amps at 12 volts) or even 468 watts (39 amps at 12 volts) – but there is no guarantee of this.
Peak Loads: Why You May Need a New PSU
With the new PCIe 5.0 connection and ATX 3.0, Intel and the standardization committee PCI SIG are also addressing load peaks – euphemistically referred to as “power excursions”. Graphic cards may briefly consume three times their continuous power. In concrete terms, this means that a graphics card with a TGP of 600 watts on a PCIe 5.0 connection can increase to 1,800 watts for 100 microseconds.
In order to handle these extremely short power spikes, a power supply must have enough extra capacitors to prevent the system from degrading and potentially freezing the PC. According to Intel’s estimates, an ATX 3.0-compliant 750-watt power supply unit could stably supply the CPU and graphics card with 300 watts each and would have 150 watts left for the rest of the hardware. According to the currently valid ATX 2.X standard, you would need at least a 1100 watt power supply unit for stable operation because of the load peaks.
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What nominal power does a power supply unit need in order to be able to stably absorb load peaks (estimates from Intel)
©Intel
According to Intel estimates, the most powerful 600-watt graphics cards combined with 300-watt CPUs could potentially require a 1,200-watt ATX 3.0 power supply. With an older ATX design, you’ll need even more buffers as the design may not have the extra capacity to absorb power spikes. Although no graphics cards available today (yet announced) can achieve 600 watts of continuous load, it is clear that the ATX 3.0 specification offers the leeway for such power guzzlers – which will then also come onto the market at some point.
ATX 12VO 2.0: Save power when idle
This feature allows direct communication between the PSU and the motherboard, allowing the system to monitor in real time how much total power is currently being consumed. On the one hand, this means that your PC can reduce its performance when consumption is low and thus save electricity. On the other hand, if your system is approaching the limits of the PSU, it can also reduce consumption to avoid overloading. Conversely, this also means that the performance of the CPU or GPU can potentially be throttled.
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ATX 3.0: The new power supply standard provides certificates for energy efficiency, noise development and housing size.
©Intel
New seals for energy efficiency, noise development and housing size
The latest major step in the new ATX 3.0 and ATX12VO 2.0 standards is the formal recognition of a competing power supply efficiency standard called Cybenetics. Most will be familiar with the 80 Plus logo, which has been around since 2004. The 80 Plus program certifies a power supply’s efficiency in converting AC power to DC power. Cybenetic’s seal of approval extends the 80 Plus program.
Which certification standard is better? Intel doesn’t have a favorite, but it’s clear that Cybenetic’s program is more rigorous, as it tests at a much wider load range than the handful of 80 Plus efficiency points. Cybenetics also tests power supplies at a higher temperature – which is closer to reality. Finally, Cybenetics also has a certification for the power supply acoustics.
This post is based on an article from our sister publication PC World, which you can read in the original here.