Your GPU is safe as long as you make sure it can stay cool. If you pump it up too much and don't give it enough room to cool off, or have enough fans, you'll ruin it. It will fail very quickly. One way to know you bit off more than you can chew is if your computer is glitchy, running way too hot, or if it crashes (the last is a given, but I feel that I have to say it just to be safe). If you're not sure what you're doing, don't do it! Overclocking is not for the light of heart! Before you Overclock make sure you upgrade your RAM to max. Your GPU relies on your RAM and it will help your overclock speed. Hope that helps.