the first thing you can try and do is fiddle with mem+cpu voltages. ECS has a notoriuos bios for showing improper voltages readings.
the PC rebooting - its actually BSOD'ing and then rebooting.
Have you tried to shut down the pc after bootup? if so , does it shut down properly or does it reboot?
check this link:http://www.tomshardware.com/forum/295475-30-h67h2-bsod#t2009367
before following steps, check:
the sticker on the ram for timings and voltages.
the stock voltage for the CPU
the build was for a friend so i forgot the max limit for the voltages on the 1155's, best to check before shooting your target