5 Long. That sounds like your CPU. Please reseat, ensure proper alignment. Check socket for bent pins.
Can you post back with a list of the parts you have got? It's very hard to offer any advice without knowing this.
To meet expansion requirements, it is recommended that a power supply that can withstand high power consumption be used (500W or greater). If a power supply is used that does not provide the required power, the result can lead to an unstable or unbootable system.
It could be a power issue if you are using a 400 watt PSU and are not sure of the power from the other one.
I know it says that it supports 2400 memory. But these series board have had problems with faster memory. If you take the memory out do you get the same thing? The CPU will only support 1600/2133 with out any adjustments. I myself had problems with 2400 memory on my Z170m-gaming 3 board. I was getting boot errors and double boots. When I put in 2133 everything was perfect after that.
Read through his thread memory problems. http://forum.giga-byte.co.uk/index.php?topic=16715.0
I have bought a brand new GA-Z170N-WIFI motherboard, but it fails to boot. The CPU fan spins up for a few seconds, then I just get 5 long beeps (at least, I think they're long... but how long is long?) and then it just resets and does the same again and again.