[citation][nom]walter87[/nom]Thunderbolt combines the PCIe standard with DisplayPort, so it is PCIe.Eventually the thunderbolt technology will take advantage of optics (its original codename was Lightpeak) and will allow bandwidth limits beyond the current 10GB/s limitation of copper wire.Thunderbolt will eventually drop in price and become mainstream and will coincide with the USB standard, just will take some time for that to happen and for the prices to drop. Intel has thunderbolt support on Ivy Bridge and all future CPUs will take the tech even further.It may never be able to stay up to par with full x16 PCIe standards in terms of bandwidth, it will provide more than adequate for mid range solutions (and anyone looking to get a high-end graphics solution anyway should be considering a full desktop at that point)[/citation]
I'm aware of what Thunderbolt is, and how it relates to PCIe. But my main point is that Thunderbolt is not an open standard, and it incurs expensive licensing fees to anyone that wishes to implement it.
On the other hand, there is an open external PCIe standard that could be developed instead that wouldn't involve those license fees and would also be capable of much higher bandwidths (up to x16 in the standard).
It seems to me that Thunderbolt is unlikely to make much headway in the market when there is a cheaper, open alternative that people could turn to, much like the competition between Firewire and USB.
In all likelihood, anyone that buys into these Thunderbolt external GPUs is going to end up with a device that is unusable in the future on the vast majority of computers that they will buy, similar to how those that bought Firewire digital cameras back in the day can't use them today without spending extra for an adapter or a motherboard that includes a Firewire port.