Chip do 250 BCLK unter Cascade;) But need high voltage, 1,76V for 5,6GHz. Have not tested Pi with Gig Board, had an MSI before, wich was totally crap, 215BCLK end
http://hwbot.org/submission/2309343_moose83_wprime_1024m_core_i5_661_267sec_899ms
More is unter Cascade not possible...