I didnt tell that I've killed my P5KC secondly

It was a modding and overclocking show here in Hungary 2 weeks ago, and we presentated Dryice and LN2 cooling. It was no problem with the E6550 CPU, I push 630fsb from the KC on DI
http://valid.x86-secret.com/show_oc.php?id=241449
620fsb 1M http://hardwareoc.hu/blog/wp-content/620-1m.JPG
more results: http://hardwareoc.hu/blog/index.php/archives/281.html
but with LN2 I've tryd to push up to 5GHz my QX6700. and I've give 1.85v+ vcore, and the mobo crashes.. one ic was burned under the heatsink









Any ideas to fix it?