June 19th, 2009 • 11:43 am
Following my post on a recurring problem in Mac OS X 10.5.6/10.5.7 with my Mac Pro’s GeForce 7300 GT graphics card, I got a number of e-mail from readers. I also submitted the problem to Apple via the Bug Reporter page. And a couple of days later, I got an answer from Apple, saying this:
This is a courtesy email regarding Bug ID# 6951559.
Engineering has requested the following information in order to further investigate this issue:
That’s a GPU restart. Have you been able to sample or Shark the app/system when it hangs? If you can ssh in, /usr/libexec/stackshot will also give you stack info for all the threads in the system. Can you please attach that information so we can take a look?
So the problem I am experiencing is a “GPU restart,” which presumably is not a very good thing, and most definitely involves the graphics card.
I replied to this e-mail saying that when the system hangs, it becomes totally unusable, so that I cannot use the Activity Monitor application to capture a “sample” of the affected application (most often Preview), but if there is a way to “sample” the application or the system remotely via ssh, I would be more than willing to give it a try, provided that they gave me some further instructions.
If, the next time the problem occurs, it does not cause a complete system hang, but only a scrambled display in the foreground application, I will also try to sample the affected application locally, provided that the video scrambling does not extend beyond that one application.
I also told them I would try to locate that “stackshot” thing remotely via ssh the next time it happens.
The interesting thing, though, is that the problem hasn’t occurred since. And the only thing that I have done is that, following a reader’s suggestion, I have opened up my Mac Pro and cleaned the dust that had accumulated inside the machine.
I didn’t really find any dust on the graphics card itself, which is a GeForce 7300 GT and does not have a fan, only a heat sink. The card is also located very close to the metallic enclosure for the RAM slots, which means that there isn’t much room for dust to accumulate anyway. Still, I tried to clean as much as I could elsewhere in the machine. There wasn’t tons of dust, but there was some.
And, since I have done that, I haven’t had a single occurrence of the problem. (It’s been four days now.) It’s not conclusive yet, but it does seem to suggest that there might be some truth to the theory that the problem might be caused by overheating of the video card due to poorer air flow. I guess we’ll see if my experience confirms this in the longer term. (It still seems strange that the problem would only have surfaced with recent Mac OS X 10.5 updates, and that some people appear to be able to eliminate the problem by reverting to an earlier version of Mac OS X 10.5. Maybe that means that there was a change in the graphics driver in more recent versions that somehow made the system more sensitive to heat issues. It’s hard to tell.)
The only problem with all this is that, since I cleaned my Mac Pro, I have noticed that its normal noise level appears to be somewhat higher than it used to be. The Mac Pro has always been a fairly quiet machine, and I have become used to the low level of noise, so I cannot help but notice that the machine is now somewhat noisier. There is a bit more of a hum than there used to be.
I reopened the machine and rejigged everything to make sure that nothing had become loose following my initial clean-up. But there really isn’t much room for anything to wiggle or hang loose in a way that would increase the fan noise level as far as I can tell. I only opened the side door, took out the graphics card and put it back in, and also took out the RAM cards and put them back in after removing the dust. I didn’t really move anything else. (The second time, I also took out the hard drives and put them back in, but that didn’t help with the noise either.)
The only abnormal thing that I noticed while the machine was open was that the three grey lozenge-shaped foam pads that are normally stuck along the bottom of the metallic door and presumably serve to provide a tight fit and prevent the door from vibrating had become unglued. But I put them back in their original position (I can still see the outline of the glue on the door) and pressed them on so that they would stay in place. So they are back in their right place now and, even though they still come easily off when pulling on them because the glue has dried, they should still work as expected when they are in place and the door is closed. So I don’t suspect that they are the cause of the increased noise.
Maybe it’s just the general aging of the machine (it’s three years old), which I might have precipitated somewhat by opening it and closing it. The weather is also warmer, so there is a higher chance of things overheating a bit and causing an increase in fan activity, although I never hear things ramping up. (The noise level is always constant, and is the same as soon as I turn the machine on, even if it’s cold.)
The higher noise level is not going to drive me crazy or anything, but it is a bit annoying that this whole problem with the NVIDIA card has caused more lasting consequences, which I don’t seem to be able to do anything about now.
As for the original problem, I guess I’ll just have to wait and see if it reoccurs. (Other readers indicate that they have been experiencing problems since the Mac OS X 10.5.2 graphics update. I do remember that at some point Apple shipped a separate graphics update, before folding it into the main system update, probably. And it’s a problem that seems to affect cards other than the 7300. One reader mentions the Quadro FX4500.)