Yes, I have the same issue. When my sound is gone randomly, I should boot with windows OS then check sound in Windows. If working in windows, your mac will recognize sound as well,.
I have no idea why it is working like that. I am regretting buying gaming7, not 5.
I just reboot into osx and it works, but I have to reboot :S
UPDATE: I just discovered unplugging and plugging back in the jack makes the sound work again