I use the overdrive at times and you are correct that it will cause the machine to crash. The first question is your video card overclockable? It may not be and that ends the story.
I've noticed that I use to be able to overclock my video card GPU by 12% but lately I'm crashing if I go over 10%. Also, my video card can no longer be overclocked more than 10% any longer. I'm assuming in my instance that time has taken its toll. I monitor heat and that is never an issue but any additional heat speeds up the decay of the components.
Are you running an ASUS card? Their GPU Tweak is better than the AMD overdrive.
BTW, I mostly underclock my video card to keep heat down in the summer. It makes no difference when there is no load on the card as the clock speed drops down well below the maximum that you set and only occasionally spikes when just doing normal applications other than gaming.