I am building a Pc with my son. Mobo is Gigabyte GA-H110M-S2H. CPU is gen 6 Intel core i5 unlocked 'k' version. DDR4 2133MHz RAM. It is not working. It is definitely not the PSU. That is pretty much the only fact. Failure mode is we get a cycling beep code on power up - 4 long and 1 short from a Gigabyte motherboard. Re-seating the RAM does not help. The system was happily booting to BIOS last week at work. The act of disassembling/wrapping/re-assembling has introduced the fault. My feeling is that a motherboard circuit break has been introduced when we fitting the CPU heatsink. Gigabyte beep codes are undocumented as far as I can tell. Nowhere is sufficiently open to help. Any suggestions to SAVE CHRISTMAS!!!!!?? Thanks - Jon