PCI-SIG concerned about potential thermal variance with 12VHPWR (PCIe Gen5) power cable adapters – VideoCardz.com

PCI-SIG investigates whether “12VHPWR” PCIe Gen5 cable adapters pose a risk of overcurrent

An article about potential problems with the 12VHPWR adapter has been published by Wccftech. The site managed to get an email from the PCI-SIG organization to its members raising a concern about the quality of the 12VHPWR connector power cable adapters.

In the coming weeks, we’re going to see high-end GPUs with TDPs reaching much higher levels than before. This is also the time when power supply manufacturers introduce brand new ATX3.0 compatible designs which have restrictive power excursion specifications and should already be fitted with modern GPU power connectors (but not necessarily).

The 12VHPWR, PCIe Gen5, 12+4 pin or 16 pin power connector is the new standard for high power GPUs such as GeForce RTX 3090 Ti, the first model to support this new connector. NVIDIA experimented with new connectors with the introduction of the RTX 30 series and its 12-pin connector, supported by all Founders Edition models.

But even the 12-pin power cable is no longer sufficient as it was based on a dual 8-pin adapter which can only supply 300W of power under ATX 2.0 specifications (plus an additional 75W from motherboard PCIe slot).

3×8 pin to 12 VHWPR adapter, source: EVGA

The RTX 40 series will need more power, at least the higher end models. The RTX 4090 has a default TGP of 450W with even higher power for custom models. For such a TGP, three 8-pin power cables are required and even the slightest adjustment of the TGP means that the power specification of 3 × 150 W is exceeded.

PCI-SIG informed their member that the organization is aware of the potential thermal variance of 12VHPWR adapters. The organization is currently investigating reports of potential risk of overcurrent when using such adapters.

Dear PCI-SIG member,

Please note that PCI-SIG has become aware that some implementations of 12VHPWR connectors and assemblies have demonstrated thermal variation, which could lead to safety issues under certain conditions. Although the PCI-GIS specifications provide the information needed for interoperability, they do not attempt to encompass all aspects of proper design, relying on many of the industry’s best-known standard design methods and practices. industry. As the PCI-SIG working groups include many knowledgeable experts in the field of connector and system design, they will review available information on this industry issue and assist in any resolution as appropriate.

As more details emerge, PCI-SIG may provide further updates. In the meantime, we recommend members work closely with their connector suppliers and exercise due diligence when using high power connections, especially where safety issues may exist.

Thanks,

The problem was explained by Wccftech who set up a test with dual 8-pin and triple 8-pin power adapters used for 600W and 450W charging respectively. For the dual 8-pin adapter, the load was even, but it exceeded the 150W power rating by a magnitude of 2. For the triple 8-pin adapter (the same one that ships with RTX 3090Ti), the power was not distributed proportionally, and it exceeded power consumption by 88% for the first 8-pin connector.

Triple 8 pin to 12VHPWR adapter with 450W GPU test, Source: Wccftech

12VHPWR connector to 2 x 8 pin adapter in 600W test load:

• 1 x 8-pin connector = 25.4 A or 304.8 W (2x increase from 150 W)
• 1 x 8-pin connector = 25.1 A or 301.2 W (2x increase from 150 W)

12VHPWR connector to 3 x 8 pin adapter in 450W test load:

• 1 x 8-pin connector = 25.34 A or 282.4 W (88% increase over 150 W)
• 1 x 8-pin connector = 7.9 A or 94.8 W (into 150 W power rating)
• 1 x 8-pin connector = 6.41 or 76.92 W (into 150 W power rating)

Dual 8 pin to 12 VHPWR adapter with 600W GPU test, source: Wccftech

It should be noted, however, that ATX 3.0 power supplies are not required to have a Gen5 connector, not even those above 450W. This has been confirmed by HardwareBusters. This means that 12VHPWR adapters may still be needed for ATX 3.0 power supplies, if for some reason PSU manufacturers do not want to fit their products with the new connector.

While PCI-SIG studies the thermal variance of existing adapters, users are advised to consider ATX 3.0 power supplies with a natively implemented modern PCIe Gen5 12VHPWR connector, as no thermal variance is observed here. The organization is due to release a report on the issue soon, possibly before NVIDIA launches its new GPUs. Hopefully this will also be thoroughly investigated by the technical reviewers beforehand.

Source: WCtech