I had same problem with my board. Used same 10.5b bios..
I didnt have any water/ice on mem slots since i had hairdryer blowin them whole session, checked that asap when 55 code came.
Didnt even have hard reset, just booted with safe settings to go into bios put some more juice and then board never booted past 55 code. (So was never able to put even more clock/volts)
Tryed already two ivys and both is alive and gave same 55 code. Then changed 2500k on it and it gave me first 55 code, then 20code and then it started just bootloop without any codes.
Now i RMA'd board fev days ago since i didnt find any solution to fix that.
Can u check do ur mobos give only 0.4volts to memslots? For me it did so thats the reason why not booting, just need to figure WHY it only give 0,4volts.