In the web release driver of GeForce GTX 590, we have added some important enhancements to our overcurrent protection for overclocking. We recommend anyone doing overclocking or running stress apps to always use the latest web driver to get the fullest protection for your hardware. Please note that overcurrent protection does not eliminate the risks of overclocking, and hardware damage is possible, particularly when overvoltaging. We recommend anyone using the GTX 590 board with the reference aircooler stick with the default voltage while overclocking, and avoid working around overcurrent protection mechanisms for stress applications. This will help maintain GTX 590's great combination of acoustics, performance, and reliability.
These are guidelines only - any overclocking/overvoltaging can void your manufacturer's product warranty.