Unusual Problem Since Upgrading

Hi there,

I upgraded to Snow Leopard quite a while ago from Leopard installed on a 2008 (pre Nehalem) Mac Pro. I don't know why its only just dawned on me to ask about this, but since this upgrade I've experienced an extremely unusual problem with my Mac crashing at random, but far from regular intervals.

Heres the specs (in case this helps):

*2 x 2.8GHZ Intel Xeon processor
*12GB DDR2 Ram
*4 x 1TB HDD's (drives 1&2 were the stock Hitachi drives that came with the Mac, the remaining 3&4 are Western Digitals added at a later date)
*2 x Nvidia Geforce 8800 GT's
*2 x Superdrives

The problem itself seems to have some kind of influence on my HDD's/partition's being picked up in finder. I'll elaborate on this shortly, but here's my setup:

Drive 1 - OSX Operating System (HFS)
Drive 2 - Partitioned into two: one half with Windows XP OS (NTFS), and the other set as FAT32 for storage exchange between the two OS's
Drives 3&4 - additional storage (HFS)

I have no idea what causes the problem, however when it does happen my Mac completely crashes and the display is sometimes distorted (pixelated/artefacts on the screen). I don't get a Kernel Panic notification and the only way I can fix this is to restart the computer.

When I restart the computer, everything appears to load fine however I am one partition short in finder (the FAT32 partition on Drive 2). Usually another normal reboot brings the partition back, however this is the only notable thing left as a result of this crash. Again, this only seems to have started upon upgrading to Snow Leopard and worked fine beforehand and because it doesn't happen often, I honestly have no idea what is causing it.

Has anyone else experienced or heard of this problem? As a drastic measure, would a complete reinstall/reformat be a wise move do you think?

Any suggestions or help is appreciated. Many thanks in advance!

Kind regards, Matt

You are likely temporarily losing the FAT32 partition due to the crash and OS X has to rebuild the directory. FAT32 is not very tolerant of crashes. As for WHY you are crashing… I'm inclined to believe it's a hardware issue of some sort. The RAM would be my top suspect. Have you ever added or replaced it? Try running the Apple Hardware Test:
Intel-based Macs: Using Apple Hardware Test

Also try MemTest:
MemTest for Mac OS X Tests your RAM

Thanks for the prompt reply. Upon turning the Mac on this morning to check emails and this thread, shortly after the same problem reoccured. Only this time, the OS fails to load at all after reboot and leaves me with half of my main display resembling a mixed up scene from an old spectrum game.

I dont have any time to thoroughly troubleshoot this at the moment, however I'll try what you suggested and go down the hardware route first (will try stripping it down to the bare essentials and adding one piece at a time to locate the problem). At least if I can get it to boot correctly, I'll be able to run the tools you suggested.

Fingers crossed and thanks for the help!

Kind regards, Matt

Nanco said:

Thanks for the prompt reply. Upon turning the Mac on this morning to check emails and this thread, shortly after the same problem reoccured. Only this time, the OS fails to load at all after reboot and leaves me with half of my main display resembling a mixed up scene from an old spectrum game.

Click to expand...

Ouch. Sounds like a more critical hardware failure has occurred. It could be the GPU or perhaps the motherboard itself. I think it's less likely to be a hard drive, but you can try just booting off an install disc. If you can boot off the install disc normally, then the hard drive warrants a harder look. You can run Disk Utility off there and verify/repair the disk if need be. Also try rebooting in Safe Mode. You could also try resetting the PRAM/NVRAM for laughs.

Startup key combinations for Intel-based Macs

Indeed, I am starting to think theres more to this problem than meets the eye. I got a few spare minutes when I arrived home from work so thought I'd give it another try. Same problem (attached a pic to this post).

With the time I had, I thought I'd try and see if I could somehow select my Windows partition to boot from, which strangely enough worked... to a degree.

The Windows XP loading screen appeared, if somewhat overcast with the same spectrum-esq display, though not as prominent. It failed to get to the login screen though, which makes me wonder if it is a general boot problem (referring to my first post: OSX and XP were on two completely different drives). Although saying that, it still doesn't explain why I get the weird display on boot prior to this.

Could very well be a GPU problem if I'm actually able to select (but not see) a boot partition at startup. Maybe a fault is triggered on the mainboard preventing further load? I guess I'll only know for sure when I have enough time to gut the system this weekend.

I'll keep you updated on the progress and thanks again!

Kind regards, Matt

One thing I did forget to mention is that a Kernel panic prompt DOES occur when the boot fails, however this is displayed on my 3rd monitor (I don't always have this on as it doubles as my TV, therefore didn't notice this initially). Again, restarting does nothing different and repeats the process.

Just for reference, this display is actually plugged into my second graphics card and does not display any symptoms outlined in the pic (even when the error message appears on it).

Problem Potentially Solved

Turns out the picture I posted was self explanatory enough. I stripped the machine down to just one HDD and one graphics card but left all RAM in place and it didn't work.

I then swapped the graphics card with the other one and it worked fine. I have yet to put the rest of the HDD's in place, however the display problem looks to be resolved.

The culprit = a graphics card (the original one I got with the Mac nearly 5 years ago, so its not done too bad really).

I'm still a little sceptical of this as from my initial post, I tended to get problems with the crash and temporary loss of my FAT32 partition upon upgrading to Snow Leopard. Maybe this was a very early sign of the graphics failing (is it normal for them to give you a few months warning before packing in?)

Maybe my initial problem was something completely different and it was just VERY coincidental that the card broke just after me posting this thread. I'll keep an eye on things for now, put an order in for a replacement card, and see what happens from there.

I'll still put the HDD's back and run the tools you mentioned lifeisabeach just to be sure as I'd hate for there to be other hardware problems present. Thanks for the help!

Kind regards, Matt