Asrock z97 extreme6 hard reboot

Hello, I'm having problems with my AsRock Z97 Extreme6 , under some graphical load my machine has begun experiencing hard reboots where the machine acts like the power has been cut but after ~ 5 seconds the computer powers up seemingly as usual.  The motherboard does give the following codes as it's rebooting 4f > 62 > 99 > A2  it's possible there was more but those are the ones i've caught.  I used the clear cmos button and it did give me  a message on the next boot indicating something was cleared.  If anyone could give me advice on how to troubleshoot the issue i'd appreciate it.