But what about all the benchmark comparisons with 16x/16x vs. 16x/4x with SLI?http://www.overclock.net/t/819348/16x-16x-vs-16x-4x-gtx-470-sli-comparison
Yeah, I've seen that before and I honestly don't know
how they did it.
It's possible that if a board is SLI certified to begin with, using a card in the x4 slot would work, but then, it should be working for you
. It's more likely that the drivers allowed it then (and they don't now
) or they used the SLI hack.