Sword I don't think that is correct...
You may be right... I was working off of memory... however, there is a difference. Doing a little research:
According to Intel:
The Intel® i7® 290 2.66GHz Bloomfield's single QPI is rated at 4.8GT/s
The Intel® Xeon® X5550 2.66Ghz Gainstown's dual QPI is rated at 6.4GT/s.
Doing the calculations for the increase, the Xeon is about 33% faster than the i7.
However, the Xeon's Gainestown processor has a dual link with a seperate memory register for each, thus giving it SIX channels, making it a six channel multiplexed system... instead of the single link and THREE channels that are in the Bloomfield i7. The result is even greater throughput. Doubling the channels probably doesn't give a 66% improvement, but I would not be surprised at 50%.
I recall reading somewhere that since the release of the i7s, Intel has unlocked a switch in them and they now will do 6.4GT/s... so it may be lower.
Does that agree with your thinking?