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What It Means To You:
ATX12V v2.0, PCI Express, and the New Motherboards

There’s a lot of confusion in the market over all of the new technologies being announced. Our advice to you: Don’t Panic! Your new motherboard should work fine with your existing power supply.

What is ATX12V v2.0?

This is the latest “desktop” motherboard and power supply specification released, a significant update to v1.3. Some notable changes have occurred:

  • SATA power connectors are ‘official.’
  • The mainboard power connector has changed from 20 pins to 24 pins to better handle loads on the PCI Express bus.
  • The 6 pin Aux Power connector has been dropped.
  • Circuitry has been upgraded to dual +12V outputs to maintain greater stability to the CPU and peripherals. In addition, overall +12V output has been increased to compensate for PCI Express expansion cards.
  • A minimum efficiency of 60% under light load is now required. This is a significant improvement.

What is PCI Express?

PCI Express is a new bus architecture introduced by Intel. At first most motherboards will continue to support both PCI and PCI Express, but eventually many if not all expansion cards will be PCI Express. The most important early point you may need to be aware of is that high end PCI Express graphics cards may require higher amperage for proper functioning, and may need special power connectors directly from the power supply to the card.

So my new ATX12V v2.0 or PCI Express motherboard will require a 24 pin power connector?

No. All new motherboards for Intel CPUs support both 20 and 24 pin connectors. The following is quoted from an Intel motherboard specification, but should be universal:

Intel Desktop Board D915PCY/D915PCM Technical Product Specification (page 66)

2.8.2.2 Power Supply Connectors

The board has three power supply connectors:

Main power – a 2 x 12 connector. This connector is compatible with 2 x 10 connectors previously used on Intel Desktop boards. The board supports the use of ATX12V power supplies with either 2 x 10 or 2 x 12 main power cables. When using a power supply with a 2 x 10 main power cable, attach that cable on the rightmost pins of the main power connector, leaving pins 11, 12, 23, and 24 unconnected.

That means you can use an ATX12V v1.3 power supply to power a PCI Express system. We recommend at least a 350 Watt SmartPower unit or any TruePower power supply.

Then what should I be careful of when using a v1.3 power supply?

First, be careful that you plug it in correctly. The connectors are keyed so that they fit only a certain way, but it’s not impossible to force them together the wrong way. Exercise all due caution.

Second, pay some attention to the load on the PCI Express bus. The vast majority of all system configurations will be fine with a v1.3 power supply. However, if you plan to use a top of the line PCI Express graphics card that draws the full power of the bus, or one that requires the special extra connector, you will be better off going with an ATX12V v2.0 power supply.

Are there other issues concerning ATX12V v2.0 and PCI Express?

The main thing to watch out for is power supplies improperly claiming to be ATX12V v2.0 compliant which in fact aren’t. Some companies have simply put a 24-pin connector on their old model power supplies so they can say they are ATX12V v2.0. If those power supplies do not meet the other requirements of the specification, then they aren’t v2.0.

Now, since most system configurations will work with a v1.3 power supply, you may be fine with such a solution—but if you plan to load up the PCI Express bus, you might encounter stability problems. The real question is: do you really want to deal with a power supply company that tries to pull the wool over your eyes?

How about BTX power supplies?

There is no BTX power supply specification. Future BTX chassis will incorporate ATX12V v2.0 power supplies. So don’t worry—Antec has you covered.