Finally we tested our golden 631 with ln2 cooling;unfortunately the motherboard wasn't modded but next time we will set everithing to take the absolute wr on p4 platform

config

-p4 631
-asus p5b@1,7V (1,6 real voltage with an exagerate drop)
-2x1Gb Cellshock PC8000
-Pc Power&cooling 1kw







here the max validation



link

wr on p4 631 and very close to absolute wr on cpuz and Pi