Run Both 8-pin EPS / CPU for OC stability
 
How many Watts does your UPS or other device show your pulling ?
 
If the PSU is having any issues ... then that is also some thing to check -->  after connecting both 8-pin & determining how many watts your pulling
 
your UPS (if you have one) could be too small
 
get a kill-o-watt type device if your UPS does not have a display
 
notice I keep saying UPS ---> OC without stable power is never stable

On Page 18 of your Motherboard Manual it says "For optimal performance with Intel® Core X-series i9 Skylake-X processors, BOTH (8-pin EPS/CPU) connectors must be plugged in with CPU power cables."
 
There is also a Supplemental PCI-E 6 Pin Power Connector at the bottom-left of that board..It provides additional power to the PCI-E slots above and beyond what they normally get through the 24-pin connector..But that's just recommended when running SLI, but connecting it anyway might make a difference too, same as with the other 8-pin CPU connector.

The second 8-pin EPS/CPU connector provides extra power for extreme overclocking, which you're not doing with your 7820X at 4.7GHz and the PCI-E 6 Pin Power Connector at the bottom-left of that board is only recommended when running SLI..But just for troubleshooting purposes I would connect them anyway to rule out not enough power as being a cause.
 
The 2 leading causes of freezing are not enough Vcore and the RAM frequency/timing/voltage not being set correctly.
 
I would bring the CPU back to stock frequency/voltage and try it..Then return the CPU overclock and bring the K|NGP|N back to stock frequency/voltage and try it..See if you can isolate one of those 2 things which may be causing the problem.
 
Also set the RAM frequency/timing/voltage to the mfgr's. rated specs in the BIOS and with a 2T/2N or 3T/3N CMD (Command Rate), never 1T/1N, at least for now.