Earlier today, SweClockers posted a story and a video of GTX 590 being blown to smitherens when overclocked to an extreme point. Swedish overclockers overvolted the each of GPUs from 0.91 to 1.2V and with only air-cooling to cool down the system, they managed to destroy the board.
GeForce GTX 590 burns out while overclocked to GTX 580 stock frequencies
We got contacted by Lars Weinand, Senior Technical Marketing Manager at nVidia EMEA who went to explain that the drivers that were given to press did not contain overcurrent protection - you can read the official statement below:
"Note on GeForce GTX 590 Overcurrent Protection and Overclocking
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. NVIDIA has worked with several water-cooling companies to develop water blocks for GTX 590, and these solutions will help provide additional margin for overclocking, but even in this case we recommend enthusiasts stay within 12.5-25mV of the default voltage in order to minimize risk.
These are guidelines only - any overclocking/overvoltaging can void your manufacturer’s product warranty."
Thus, this scenario should not repeat if you use official WHQL-certified drivers such as 267.85 for 32-bit Windows and 64-bit Windows 7.
Truth to be told, it would be interesting to see how would AMD's Radeon HD 6990 fare if the GPU voltage would be raised by 24% and left on air-cooling alone.