he's not talking about QPI, he's talking about turbo mode, which changes the clock multiplier.
edit: sigh nevermind. i get what you're trying to say, but it's not that simple either. All 1156 xeons feature turbo mode. The cheap 1366 Xeons with dual QPI (E5502 to E5506) do not have turbo mode. 1S Xeons like the W3520 only have 1 QPI link, but they do have turbo, and the L-series have turbo. all the becktons have turbo.
if you simply type in the model number of the xeon you're looking for, intel's website will tell you "how high" they can turbo.