.Core i7 4790Full spec sir nung unit mo sir? Kadalasan Resetting the BIOS will fix the powering off issue.
Remove mo muna sir ung battery, then manually short mo using either a scissor or wire. you can search it online kung pano i manual short.
Pede din reseat mo ung cables. baka may loose ka or di nakalapat.
Clean the ram sticks also.
If newer model board mo, may debug LED dyan if may nag lit, you can diagnose it easily
san po makita yun?check mo yung vrm ng mobo mo mostly nagilaw yung led non nakaindicate if ram,cpu,vga ang problema
kakapalit ko lang last month ng thermal paste and 1year palang Yung Aio ko wla din naman leaklinis loob ng cpu lods then check mo heat temperature mo baka mablis na siya mag init lagay ka bago thermal paste moslty twice a year ka dapat nag papalit ng thermal paste sa heat sink mo