clock watchdog timeout overclock

[Henry97]

I've been trying to overclock my desktop and raising vCore more than 1.355 or Freq more than 4.6GHz will give me one of 2 errors (clock watchdog timeout or device stuck in thread driver).
Does this mean I've reached my max stable OC or is it my MOBO or PSU who cant handle more power?

I know that .1 or .3 GHz won't make much difference but I would still like to know my bottleneck 😛

Thanks

MY SPECS:
i5 6600k @ 4.6GHz 1.355V
MSI Z-270 Tomahawk
XFX ts 80+bronze 550W
MSI Rx 480 4G Gaming X
16 GB Tridentz RGB RAM 3000MHz CL16
Corsair h100i v2
3 1000RPM fans (NOX)
2 corsair fans (liquid cooler stock)
m.2 evo 960 250GB
10k rpm hdd
7,2k rpm laptop hdd
3.2k rpm laptop hdd
Mechanical Keyboard (Red backlight)
Steelseries Rival 300 Mouse
HyperX cloud II

 

[Henry97]

Also I'm getting temps under 73 while gaming