Has anyone tried editing the voltages on their cards to ensure that the freeze/crashes aren't caused by wild swings in OSX's power management? I booted into Windows to show you what I've edited. While this didn't give me complete stability against the Fermi Freeze in either Snow Leopard or Lion, it definitely helped improve both stability and overall GUI performance. The default p-state for GTX460 is 50mhz, single-handedly explaining why many Fermi card users find animations like swapping spaces and opening dock folders somewhat stutery at first.
I used GPU-Z to extract my BIOS and the latest version of NiBiTor to edit the voltage and speeds.
You can find a guide to editing your card's BIOS here -
http://forums.guru3d.com/showthread.php?t=336117
The two big takeaways are this - I bumped up the lowest voltage and chip at the lowest state to be closer to the next state. What was initially 50mhz at 0.875V is now 200mhz at 0.925-0.95V. While I raised the voltage on the lowest state on my card, I was able (after much testing) to
overclock my card while also lowering its top voltage - so 720mhz @ 1.1V to 800mhz @ 0.9875V.
Overall I tried to keep the voltage steps relatively smooth and with overlap, ensuring that there's enough power to spare if the card ever quickly bumps from it's low state to high. Additionally, I paired this with an edited AGPM that essentially removes the 200mhz default. The GPU seems to remain at 405mhz even when sitting at the desktop with no movement. For those worried about temps - there doesn't seem to be much difference between Windows and OSX while engaging in my usual geeky computer activities - reading news sites, occasional Photoshop work, email check, an occasional 3D screen saver when I walk away, etc. Right now the card sits at 405mhz/200mhz (gpu/mem) at 41C in Windows. Before I left OSX to write this post, the GPU was at 405mhz/???mhz and reading 38C.
I hope this helps some of you!
Oh, once you edited your BIOS, you can reflash your card's BIOS right from Windows. I've done this dozens of times with no corruption, but YMMV. I will not be responsible if your card goes up in smoke. In fact, I may laugh.
You can find the Windows version of NVFlash here -
http://www.techpowerup.com/downloads/2133/NVFlash_5.118_for_Windows.html
As I wrote earlier, some combination of my card's edited BIOS, my edited AGPM settings is allowing me to run Mountain Lion with none of the system-killing instability of the past. I've only seen one glitch coming out of a screen saver, but that issue resolve itself quickly. No Kernel Panic since I moved up from Lion
