Shulou(Shulou.com)11/24 Report--

CTOnews.com, July 3, igor'sLAB revealed ahead of time the upcoming PCI SIG CEM 5.1 specification (which serves as the basis for ATX 3.1) and the PCIe Base 6 draft, which includes many unexpected designs.

First of all, the criticized 12VHPWR connector in the RTX 4090 series of high-end graphics cards will be removed, and the 12V-2 × 6 connector will appear as a substitute.

The new CEM 5.1specification uses the new 12V-2 × 6 connector to replace the existing 12VHPWR connector, and as a basic specification, PCI SIG directly defines its commonly used form factor, maximum and continuous power parameters, so it will not be so confusing.

This connector can support 675W video card (connector 600W+PCIe power), while the motherboard PCIe slot (PEG) still has a maximum power of 75W. For comparison, the previous CEM 5.0had a maximum power of 600W.

In addition, CEM 5.1 has updated standard measurements of maximum and continuous power to match existing form factors, thus maintaining specification consistency.

In terms of compatibility, hardware that does not support 12V-2 × 6 will not be affected in any way, and it will have a small impact on 150W and 300W versions of hardware that follow basic specifications to implement 12VHPWR pin detection, but any information related to the graphics card is not clear.

It is said that the impact on the software will not be seen unless the software supports the CEM form factor, while software that uses the Power Budgeting Sense Detect Register (Power Budget perception Detection Register) needs to be updated to reflect the new defined coding; and software that uses the Connector Type field needs to be updated to support additional connector type coding.

But again, we do not yet know any information related to the video card and power supply. Because so far, it has not been applied anywhere. Foreign media believe that the configuration memory test may need to be updated to avoid marking the expansion card using the new code as a fault.

Simply put, the new 12V-2 × 6 power connector will also provide continuous current of up to 55 A to power the expansion card on the 12V auxiliary line with a maximum power of 600W. CTOnews.com summarizes the power requirements for connectors and wires as follows:

Current rating for current pins (except sideband / sideband contacts): the minimum value for each pin / position is 9.2A, and when all twelve contacts are activated, the maximum temperature rise does not exceed 30 °C in a 12 V DC circuit.

The connector body should have a label or raised H tag to indicate support for 9.2A / pin or higher. See the marking position of the 12V-2 × 6 right-angle (R / A) head in the image above.

Due to changes in contact resistance, a single pin may withstand more than 9.2A current, depending on the uneven cable contact resistance, but the total current must not exceed 55 A RMS in either direction. This also solves the problem of measuring and requiring the change of contact resistance.

The cable assembly integrator must ensure that assemblies, including 16 AWG wires and pins, meet the minimum current and maximum rise temperature requirements specified above.

Locking connector holding force: minimum 45.00 N when pulling connector axially

It is said that the wire or plug may also change, and two different versions are likely to be available. For example, in option 1, we can see that there is a 0.7 mm shoulder below the sensor pin, but option 2 does not have this design. The same is true for spring contacts.

Of course, the biggest change is the so-called connector, which also includes the interface. First of all, the 12V-2 × 6 connector can conditionally be compatible with the old graphics card with the 12VHPWR connector, and the current 12VHPWR power supply, wire, and adapter can also be more or less compatible with 12V-2 × 6.

As before, twelve large contact points carry circuit tracks, while four small contact points carry side-band signals. This is the biggest change.

It is worth mentioning that the 12VHPWR coding update is also designed to accurately reflect the released CEM 5.0 (because the basic specification is even inconsistent with CEM 5.0). Expansion cards with 150W or 300W power apply the new rules, and external circuits are still required to detect 150W cards. Of course, 12V-2 × 6 is still not compatible with PCI Express 2 × 3 and 2 × 4 PCIe (auxiliary) connectors. Because the power pin spacing of the 12V-2 × 6 connector is 3.0mm, while the contact point spacing in the 2 × 3 and 2 × 4 connectors is 4.2mm.

In addition, the 12V-2 x 6 connector has the same external size, and the final contact point of the sense pin is still located at 3 mm to ensure compatibility; but the tip of the sense pin is offset inward by 1.7mm, increasing the distance by 1.25mm; the pin, the first contact, which is actually behind the tip, is now even located about 2 mm behind the outer edge, which can lead to higher safety.

300W power can be achieved by grounding pin 0 and keeping pin 1 open. In addition, the 150W circuit is tricky and novel: pin 0 and pin 1 are directly connected and not grounded, which may require a new cable or dedicated power supply:

In terms of safety, in order to avoid unnecessary pressure on the contacts, it is officially stipulated that the cable bundle should not be bent immediately after it is drawn from the back of the connector and should not be stretched or restricted in any way.

The IPC / WHMA-A-620 standard specifies the manufacturing practices and requirements of cables, wires and cable assemblies. The standard describes the manufacturing methods, testing and acceptance standards for clamping, mechanical fastening and welding connections, as well as assembly activities related to cable and wire assemblies (appropriate fastening / retention standards).

It is said that changes in contact resistance in cable assemblies can lead to an imbalance of current between contacts and may cause individual contacts and / or wires to exceed a specified single pin current. In addition, because the bending and / or lateral loading of the cable assembly connected to the expansion card increases the current imbalance, specific wires, connectors, and manufacturing processes must be designed for the cable assembly. to withstand current imbalances caused by changes in contact resistance and lateral loads.

In addition, there are regulations on temperature limits. If the heating of the circuit board (shunt more than 100 °C) and the external influence of the side of the circuit board (not just the changing current and contact resistance) may cause pin heating are taken into account, then the video card should indeed adopt a different design in terms of power connection.

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