[UPDATE: Information on updated drivers can be found here.]
I'm getting a steady stream of reports in from NVIDIA users that the latest 196.75 drivers can cause severe cooling problems, even possibly resulting in the death of the hardware.
The problem seems to be related to the fan controller, causing the fans to slow down, and even stop. This happening while the card is in use is a very bad thing indeed, and can cause poor performance (as the GPU tries to cool itself down by reducing power) and possibly even overheat your GPU to the point where the card stops working.
NVIDIA 196.75 drivers were released on March 2nd, and have now been removed from the download site. If you are running these drivers it is HIGHLY RECOMMENDED that you uninstall this driver and immediately downgrade to the 196.21 drivers.
Here's the official statement from NVIDIA:
We are aware that some customers have reported fan speed issues with the latest 196.75 WHQL drivers on NVIDIA.com. Until we can verify and root cause this issue, we recommend that customers stay with, or return to 196.21 WHQL drivers. Release 196.75 drivers have been temporarily removed from our Web site in the meantime.
If in the past few days you're upgraded your NVIDIA drivers and your PC has since died (and you're somehow reading this ...) then this could be the cause of your problems. I've already received several reports from gaming enthusiasts who claim that their systems died shortly after installing these drivers, which while not conclusive, is certainly enough indication to me that these drivers could be very toxic and should be avoided.