PCI Express Group Proposes External PCIe Cable Standard

PCIe SIG Opposes Thunderbolt with Own Standard

by Anton Shilov
06/22/2011 | 05:24 PM

At the annual meeting, PCI special interest group (PCI SIG) announced plans to develop a PCI Express-based interconnection standard for external devices. The standard will directly compete against Thunderbolt (co-developed by Apple and Intel), its successors as well as USB 3.0.


The proposed external PCI Express specification is projected to be based on the PCIe 3.0 technology and will support four lanes with transfer speed of up to 32Gb/s, according to EETimes. Initially, the interconnection will use copper wires, but eventually, as the speeds get higher and when the technology adopts the PCI Express 4.0 protocol, wires may be changes to optical. Naturally, the future flavours will challenge not only Thunderbolt with its 10Gb/s interconnection, but also its successors.

"This will help proliferate PCI Express into new business opportunities. Right now we see a need from our members," Yanes said, declining to comment on Thunderbolt directly. There are solutions [like this] in the industry - Thunderbolt is one of them, and some companies are doing own thing," said Al Yanes, president of the PCI SIG.

Unfortunately, the cabled PCIe 3.0 will not support devices with power consumption higher than 20W, which means that it will be impossible to implement external graphics cards into the power envelope of one port (it is physically possible while utilizing several ports with separate power supply circuitry) and therefore the connector will only support mass storage devices, e.g., SSDs, flash sticks, cameras, etc.

"The big issue here is proprietary versus industry standard. It is not clear third parties will have access to Thunderbolt on the same basis they get access to PCI Express," said Nathan Brookwood, the head of Insight64 analyst firm.

Details of the new standard will be defined by a working group now being formed. The group is expected to deliver a standard system makers can implement in products before June 2013. Developers have been working within SIG for several years now over external implementation of the PCIe, something the standard was not tailored for.

In spite of overkill speeds even for 2013, the PCI SIG wants to position its external PCIe 3.0 for consumers. The reason for that is to enable thinner devices with higher speed cable interconnection. It is in question, whether by 2015 there will be no wireless networks to transfer data at decent speeds, considering the fact that multi-Gb/s networks are available now.

"The motivation for the PCIe cable wasn’t spawned due to Thunderbolt, it was more about the shift to thin notebooks and tablets that means you just can't mechanically package things the same way we used to. Thunderbolt was interesting, but it did not solve the problems we have the way we want to have them solved," said one source close to the effort who asked not to be named.