| Generally, we prefer not to comment on competitor's products, but we get this question so often that we thought it was worth an explanation.
The Red Rocket is a PCIe 1.1 x8 card. In a Mac Pro, it likes to be in an x8 (or faster) slot and will give a warning message if it is not. Does this warning have any meaning in a Thunderbolt expansion chassis, which may have either an x4 or x8 slot?
In a Magma chassis, the connection to a Red Rocket is PCIe 1.1 x8 which has a bandwidth limit of 20Gb/sec. This bandwidth may get as far as the Thunderbolt chip but it is throttled down to the 10Gb/sec bandwidth limit of the Thunderbolt channel dedicated to PCIe. You can't get more bandwidth than the slowest link in the chain. You get transfer, wait, transfer, wait, transfer, wait\u8230 an aggregate bandwidth of 10Gb/sec.
In the Sonnet chassis the connection at the Rocket is PCIe 1.1 x4 which has a bandwidth limit of 10Gb/sec. This bandwidth can be passed through the Thunderbolt chip at full throttle at the same 10Gb/sec bandwidth of the Thunderbolt channel dedicated to PCIe. You can't get more bandwidth than the slowest link in the chain. You get transfer, transfer, transfer, transfer, transfer\u8230 an aggregate bandwith of 10Gb/sec.
If there was any difference in performance, Sonnet would have designed a bridge from Thunderbolt to x8, but Sonnet's tests showed that there was no difference in performance between a Thunderbolt PCIe bridge to x8 and a Thunderbolt bridge to x4. The limit is Thunderbolt, so Sonnet put money into other aspects of the Echo Express Pro (designed and manufactured by Sonnet in California) that provide benefits to the user\u8212 like a rugged chassis, automatic temperature-controlled variable-speed fans, three fans for quieter operation, generous ventilation holes so that a fan card in one of the precious PCIe slots is not required, and a value price point. |