i have a H81M-ITX here thats been fine for 6 months
now it powers down & restarts continually without even posting

swapped psu, changed ram, reset bios, pulled it out of case & set it up, got it going, ok case short,
put it back in, works fine, today, reboots again?
its got me
im trying everything i can not to blame the board, cpu is under 40c
chances are ipp pull it back,out & it will work again, for a bit
any ideas