No signal problem, Ram issue?

I am building a new pc, with my old system drive rest was new parts. But after turning the power on, the monitor detects no signal. I am using intergrated gpu right now, but as I only install 1 ram alone, I can boot into win10 no problem, but with 2 ram installed I got no signal error.
Anyone can help me to detect where the problem is? The ram set? mobo? or psu?
my build as below:
cpu i5 6600k
mobo asrock z170 pro 4
ram 2X8 gb ddr4
psu antec eco neo 550w
thanks for any input

yeah just had a similar problem with ddr3 added 2 stick and wouldnt boot blank screen but took out 1 stick and it worked it straight away i would look at trying the other stick alone if it still shows blank screen then the memory is dud