So, I've been following a freezing issues thread, and noticed some interesting behavior, but that thread is getting a bit off-topic, so I'll summarize a bit here... I have a 15" i7, HR Antiglare, self-upgraded to 8GB, otherwise stock. I've had ~5 freezes in the month or so I've had the machine. I did a hard reset other than with the last freeze, having read that people's machines came back to life...and lo and behold, after about 8 minutes, my machine unfroze. I've noticed a few things relating to the switching, and also discovered that I can gain a huge amount of battery life and drop my system temperature by forcing Intel graphics. Some people have suggested HD issues. This was definitely NOT the case for me, as I was able to ssh in from another machine while it was frozen, and everything seemed to be working fine...other than the kernel and the Dock eating up CPU. PID COMMAND %CPU TIME #TH #WQ #POR #MREG RPRVT RSHRD RSIZE 78543 Dock 100.6 08:15.22 5/1 2/1 138+ 309+ 4856K+ 55M 16M+ 0 kernel_task 100.5 05:01:52 87/5 0 2 593 98M 0B 408M Also, I've seen the following spammed in my kernel.log after rebooting, repeated several times from before the forced reboot: Apr 28 23:16:03 lucid kernel: NVDA(OpenGL): Channel exception! exception type = 0x8 = Fifo: Watchdog Timeout Error Apr 28 23:16:03 lucid kernel: 0000006e Apr 28 23:16:03 lucid kernel: 00000010 00008597 00000474 00000000 Apr 28 23:16:03 lucid kernel: 0000047e 00001528 00000000 00000009 Apr 28 23:16:03 lucid kernel: 00000000 00000000 01000003 This points to graphics. I've installed gfxCardStatus, which lets you choose between auto, Nvidia-only, and Intel-only. (Which of course the Energy Saver pref pane only lets you do the first two of.) It also displays what's currently in use, and if on Nvidia graphics, what apps are causing the Nvidia chip to be selected. I'm currently running the 64-bit kernel, and haven't seen the same error message. I suspect that the 64-bit drivers are just not reporting errors the same, because the freezes have been the same with both the 32-bit and 64-bit kernels. One interesting thing I noticed is that keeping X11 open, even if I have no X programs running, forces the machine onto Nvidia graphics. I always have X11 running, so chances are that until I installed gfxCardStatus, my machine has been on Nvidia graphics 100% of the time other than if I was rebooting and hadn't launched it yet. I'm now running with graphics forced to Intel-only. I'm hoping this will prevent crashes, but there's no way to know for certain. Running Nvidia-only (which you can do from the Energy Saver pref pane of course, not requiring the 3rd party app) could also prevent crashes...but I suspect it may not due to the above info about having X running. Switching to Intel only has significantly boosted reported battery life (running a task and unplugging for a few minutes, then looking at the estimate.) I tested under two conditions: system "idle", which for me means having Terminal/Safari/Mail/Adium/iTunes/iCal/Address Book/X11/Xcode open but not doing anything, and playing a 720p h264 movie in mplayer (with the above apps open as well.) For the "idle" test I had the LCD at minimum brightness; for the mplayer test, I had the LCD at 25% brightness. With the default auto-switching, and thus Nvidia being selected, my reported battery life "idle" was 6:42. When I switched to Intel-only, this went up to 9:08. With mplayer, the difference was even more striking. With auto-switching (and thus Nvidia), reported life was 3:30. With it forced to Intel, reported life was 5:38. Graphics output/system speed/etc all remained the same, because mplayer was doing software decoding. (Note that mplayer also forced Nvidia graphics, so even if I'd quit X, I'd still be stuck with Nvidia without having forced Intel with gfxCardStatus.) On top of that, my system is significantly cooler forced to Intel-only. Right now I'm "idle" with the enclosure at 35C and the CPU at 42C. Previously, when I had it on auto (thus Nvidia), "idle" would have the enclosure around 37 - 40C and the CPU around 51 - 54C. I *never* saw the CPU temp drop below 50C until I switched to Intel graphics only. So the Nvidia GPU is probably located somewhere near the CPU and putting out a ton of extra heat that the CPU is partially absorbing. The machine is noticeably cooler as well, on the bottom towards the back in the center, where it's always had a hot spot. (I'm using iStat Menus to get temperature info.) So...switching to Intel-only at the very least has given me a significant battery boost, AND dropped my system temperature overall. Lower CPU temperature also means that TurboBoost can function longer, too. So not only does Apple have to fix the freezing issue, but it's obvious that the switching is extremely non-optimal, given the heat and battery life differences I noticed.