Crucial Ballistix DDR3-1600 / PC3-12800

[v_parrello]

but same with E6700 L629B079 max 514FSB on other boards, 485FSB on Blitz Extreme, Q6600 B3 ES 501FSB on P5K Deluxe, 485FSB max on Blitz Extreme, Q6600 G0 L725A903 493FSB on Blitz Extreme.

Maybe your Blitz Extreme it is not so lucky it is one of the possibilities.

We tried with air and water cooling:
E6420 around 550 FSB in both motherboard (Blitz Extreme and P5K3)
E6850 around 540 FSB (no tests with P5K3)
E6600 560-570 FSB on DFI 965P but only 495 on Blitz Extreme.

So at the end in our tests Blitz Extreme performs well only with some CPU types. For our motherboard is not a trouble of FSB wall related to motherboard, because Blitz Extreme in our hands was able to reach 550 of FSB.

For these reasons I am thinking about some trouble with bios CPU support. I think you have to try with E6420 or E6850.