Mac Pro unexpectedly enters sleep mode

Question

Ok so I installed Leopard last weekend on my Mac Pro and all initially went well with the install. After installation was done, software update appeared and stated I had approximately 4 downloads to install. So I had done this and prepared to reboot. Before rebooting, a window appeared stating that it needed to update the Boot cache. So I clicked on "OK" and the computer went into its shutdown sequence. When the computer reset, I noticed there was no start up chime and the system just sat there with a black screen. I thought perhaps it was updating the boot cache and it may take a while to finish. So I went afk for about an hour and came back. Still nothing. This is when I knew there was something seriously wrong with my system.
After speaking with Apple support and trying several things to get it to boot, the support rep stated that it will need to go into the shop for repairs. I had taken it to an authorized service center and they diagnosed the problem as a bad logic board. They had replaced this and had ran their diagnostic tools on it to make sure it was running normally. They kept it overnight and ran Apple Service diagnostics in a repeating loop on the system. They had also cold booted the system 30+ times per the work order.
After I brought it home and booted it, everything was seemingly running fine. Then I received a page from work (I'm a support rep) which required me to boot into Windows using Boot Camp to solve a client's problem. After I had done this, I booted Leopard back up and was playing around in it for a few minutes to check out some of the new features. I had then ran World of Warcraft to play a bit and to check out the performance increase in Leopard. After about 5 minutes of playing, my system unexpectedly entered sleep mode. Obviously I was confused so I had brought it out of sleep mode by hitting the enter key. The system came back for about 2 seconds and immediately went back into sleep mode again. This happened about 4 or 5 times before I finally shut the system down.
The first thing I did after reboot is to check the energy saver options. Both hard drive and monitor energy options were set to "Never". I then checked for software updates. There was both an SMC firmware update and a Boot Camp EFI(?) firmware update. I had done the SMC firmware update first and then after successfully updating this, I had done the Boot Camp firmware update. After reboot, the system went into sleep mode on its own approximately 5 minutes after reboot. This time I had made sure NOT to run my game as I had a suspicion that this could be causing the problem. It entered sleep mode anyway unexpectedly. After waking it up again by hitting the enter key, the desktop appeared again for about 2 seconds before going right back into sleep mode. I called the service center again and they said I would have to bring it in for them to look at. Needless to say, I am NOT very pleased.
Has anyone ever heard of anything like this happening with a Mac Pro? I had never had any problems when I was running Tiger with any application, not even my game. The service rep where I took it said it was just bad timing that the logic board went during my OS upgrade and that the two had nothing to do with each other. My brother has a Mac Pro as well and he had upgraded to Leopard. Of course his computer works fine where mine is a sleeping fool. Does anyone have any ideas or theories as to what could be causing this? More importantly, does anyone have any suggestions on how I might be able to fix this on my own? If you could please let me know, I would appreciate it. Thank you in advance for your time.

Answer 1

Wow, who are you dealing with? The first time my logic board was replaced, the techs never bothered with looking at anything else as being the problem. However, when I pointed out the power supply fan problem, they focused on that being the cause of the problem and fixed just that. I was somewhat concerned as I know some of these techs do not look at other parts of the machine as potential problem causers. I was afraid that I would hook up my system only to experience the same problem as before. Luckily, that was not the case.
I am glad that your system appears to have the same problem as mine did. I would suggest that if you take it back to them again for a fan fix to have them run the system for about an hour after replacing it. They should be opening apps, checking the iStat widget, etc to try and make it break. If they can't after an hour or so, I think it should be ok.
This whole ordeal makes me question the quality of parts used by Apple. My brother has an iMac G4 where the hard drive died after 2 months of getting it new. Now this issue with mine and yours with the bad logic board and the power supply fan. Who knows how many other customers report hardware related problems?