AMD in a comment hoped to minimize the impact of Intel's Thunderbolt technology. It argued that the 10Gbps bandwidth wasn't necessarily enough for video as a DisplayPort connector could handle up to 17Gbps, limiting what a screen attached in a Thunderbolt chain could manage. Any other devices in the link could further reduce the bandwidth and would rule out multiple displays, conveniently including multi-screen arrays using its own Eyefinity technology.
It pointed out also that the headroom in the initial Thunderbolt spec wasn't much larger than for PCI Express, SATA or USB 3.0 and could trigger slowdowns if there were more than one device working at the same time.
"Many AMD-based platforms support USB 3.0 which offers 4.8Gbps of peak bandwidth, AMD natively supports SATA 6Gb/s with our 8-series [system] chipsets," a representative said. "Total bandwidth stated for a Thunderbolt channel is only 20 percent higher than one PCI Express 3.0 lane and about 52 percent higher than a single USB 3.0 port."
It went on to argue that the bandwidth of other, existing standards was enough and, since it was separate, could theoretically offer more than Thunderbolt.
AMD's comments have some merit as few users may be willing to daisy-chain more than one main device and a display. The chip designer nonetheless has a vested interest in trying to minimize Thunderbolt since it would have to buy controller chips from Intel and reward its opponent. Its graphics cards regularly depend on Mini DisplayPort to allow multi-display from a single card and might put pressure on it to incorporate Thunderbolt on future Radeon hardware or else help third parties use it.
Apple, the first to use Thunderbolt in its new MacBook Pro, has focused more on the ease of use of merging displays and a high-speed interface into a single, small connector. Notebooks have rarely had the option of using RAID arrays or other very bandwidth-heavy devices since they rarely have ports fast enough to support more than one drive.
