Now I'm more confused: the control panel tells me that 331.01.01f01 is installed, and that it's the stock OS X driver. It's also the latest one listed on nVidia's website.
The NVIDIA Driver Manager control panel has several functions:
Let you choose between the nVidia driver and the Mac OS X driver
Let you enable ECC on the K5000
Let you check for updates of the nVidia Web Driver
The first tab "Graphics Drivers" shows you which driver your system actually uses. The third tab "Updates" shows you, if the nVidia Web Driver is up to date. It is possible to have the latest nVidia Web Driver files (331.01.01f01 at the moment) on your system and using the earlier Mac OS X driver (310.40.25f01).
Under certain circumstances the older Mac OS X driver is used even if you have the newer Web Driver installed. I noticed this once on my system and had no reasonable explanation. But after switching to the Web Driver the setting remained so after reboot.
You can look in the "Apple System Profiler", too. There is a section called "Software/Extensions". It is a long list. Scroll down until you reach the extensions beginning with the name "NVDA
". In the column Loaded you can verify which driver is currently used by your system. And you see the Apple supplied driver and the nVidia Web Driver. Obviuosly, the Web Driver has the suffix Web attached.
I hope this clarifies some of the confusion.
BTW - On my EVGA Geforce 680 GTX 2GB (flashed with the official BIOS) the DVI output (dual-link) works as expected.