Comparing PCIe cable, Thunderbolt
"The big issue here is proprietary versus industry standard," said Nathan Brookwood, principal of market watcher Insight64 (Saratoga, Calif.). "It's not clear third parties will have access to Thunderbolt on the same basis they get access to PCI Express," he said.
Indeed, one chip maker on the show floor of the annual PCI SIG developers conference here said his company is working on a Thunderbolt design. However, the gating item to getting it completed is getting access to the technology from Intel, he said.
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," said one source close to the effort who asked not to be named.
"Thunderbolt was interesting, but it did not solve the problems we have the way we want to have them solved," the source said.
Thunderbolt uses a router chip on either end of the connection to support multiple protocols and daisy chaining of devices. Apple "is fine with the extra cost of the router chips, but we don’t need [the multiprotocol support] and a couple extra chips don't make business sense for us," the source said.
The use of four parallel channels and a thinner cable and connector are also expected to give the PCIe approach a leg up over Thunderbolt in throughput and ease of supporting thin systems.
Intel introduced Thunderbolt in February when Apple debuted MacBook computers using it. It uses five wires to support two 10 Gbits/s bi-directional channels on a common transport layer that can carry 4x PCIe Gen 2 or DisplayPort traffic.
A handful of system makers said they support Thunderbolt including executives in Canon's camera and video group. LaCie, Promise Technology and Western Digital said they will support the interconnect in external drives. A handful of other companies said they will provide support in mainly software products.
Other than Apple, only Sony has so far been reported to have plans to support Thunderbolt. The PCI SIG's decision to create a competing technology suggests mainstream PC makers on the PCI SIG board such as Dell and Hewlett-Packard do not want to adopt Thunderbolt.
When Thunderbolt was announced, at least one top PC maker said privately the company is moving ahead with USB 3.0 as a fast external interconnect. It is less interested in Thunderbolt than in seeing Intel more aggressively support USB 3.0, he said.