Krunz, you should try upping the bus changing your QPI and ram ratio. You may see better results then just raising the multi if these cards are bandwidth starved. For example, 200mhz x22 with a 10:2 Clock:ram ratio will net you the same CPU mhz and run your ram at its rated 2000mhz, but you can raise your QPI link into the 6ghz+ range as well as upping your Uncore speeds. Might free up some more bandwith for those QuadSLI'd cards.
Might take a bit more tinkering, but I think you'll see better benchmark results in return.
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