Gigabyte 970a-ud3p system restart issue

Hello Forum,

I am new to overclocking and today I thought I would mess around with settings to see how to overclock my cpu.

All my bios settings are on default with turbo core set to off and voltage set to auto. I didn't touch any other settings but just increased the multiplier to get the system running at 4ghz. 

I did a 15 minute prime 95 stress test and got no errors, with the core temperature not exceeding 43 degrees C.

I then went back in to the bios and bumped it up to 4.2ghz and did the stress test again and had the same results.

I do understand that I have to set the voltage manually but I'm not very experienced with OCing yet so will have to read up on it.

The problem I am having is that after overclocking, every time I restart my PC it seems like it shuts down for about 5 seconds then turns on. The power light and fans turn off. It does boot without problems after it does this.

Normally when I restart my PC it restarts without the power light and fans turning off.

I would appreciate it if someone can shed some light on why this is happening?

My System specs..

OS - Windows 7 64 bit
CPU - AMD FX-8320
Motherboard - Gigabyte 970a-ud3p 
RAM - HyperX Fury 2x4 8GB 1866mhz
SSD - Samsung EVO 840 250GB
GPU - Sapphire AMD R9 280 Dual-X
CPU Cooler - Hyper 212 Evo
PSU - Antec HCG 620W Modular

BIOS version is F1, I updated this via the gigabyte utility in Windows.