Tonight I benched i7-920 on Extreme with dry ice cooling, and I found some sort of MoBo cold bug:
system can't boot if Vcore > 1.53875 (BIOS). It goes to infinite power on/power off loop with following error codes: 11, 22, 55. Tried F4m instead of F5e and nothing changed.
This Vcore limit is low for my chip in 2D benches and cold water looks better then dry ice for it. DI clocks are 4500 Mhz for 3DMark 05 and 4450 Mhz for 3DMark 06, same as cold water.
Also processor thermal diodes can't show temps lover then -10*C. Temps are -59*C by thermometer, -10*C by RealTemp 2.90b, -60*C by BIOS monitor.
Is anybody here benched i7-920/EX58-Extreme on lover temps, on cascade or LN2? Do you have same issues?