Mac Pro boots to black screen

Four times out of five, on average, the Mac boots to a black screen -- a 30" Cinema Display.

I believe the computer is booting all the way up, because I have the front power button set to put the computer to sleep, and when I manually power down the machine using the power button, the Mac will go to sleep first.

Also, the Mac will go into Firewire disk mode when connected to my MacBook.

The "boot-to-black-screen" occurs from cold or warm boots.

I've tried both 10.5 and 10.6 OS -- no difference, results the same on both.

Here's what I've tried:

Reinstalling and updating OS both 10.5 and 10.6
PRAM zap
Pulling all USB and firewire peripherals off the computer (except the Apple Wired Keyboard that shipped with the PC) -- Mac promptly booted to black screen, so peripherals are not the issue.
Changing displays (in this case, a Samsung 17") -- same result

I have tried booting to the Apple Hardware Test on my commercial Leopard DVD and Snow Leopard DVD, but the machine will not boot to this (the Leopard disk will boot the AHT on other Macs). I no longer have the original CDs that shipped with the Mac.

I've suspected the video card, but according to other posts, apparently this is not the cause.

I'm now suspecting a motherboard firmware issue.

Before this, the Mac Pro was having a related issue pertaining to VMWare Fusion, wherein the Mac would occasionally not wake from sleep, logging a VMWare Fusion kernel crash.

For the moment, I'm not shutting down the Mac Pro, just turning off the Cinema Display. I've left this computer running for up to two months without a reboot, so I'm confident that it will stay up and remain stable.

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d4nnyoAuthor Commented:
PS -- my Mac Pro is an early 2008 8-core 2.8, with 14 GB RAM, and ATI 2600.

I did post to the Apple Discussion board last week, with no solutions offered yet.
I would still suspect the video card.  if you have access to one that will work in the Mac Pro, it would be a simple test.  I'm running a similar Mac Pro to yours and have not had any video issues.
d4nnyoAuthor Commented:
Thanks. No card to test right now. I'm thinking of investing in a 4870, but my Mac Pro is so mice and quiet. Any idea of how much fan noise the 4870 puts out?

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Can't speak to the 4870. I have a 3870 in mine. It's louder than the card that came with the Mac Pro since this one has a fan and the other one doesn't. But I'm in an office so there is quite a bit of background noise. Still... I can hear the fan when it runs.
Do you hear a chime noise when it boots?

Do you ever get the grey screen? If so try holding down cmd + v and that will take you into verbose mode and you can see what the issue is at the bottom of the list?
could it be a monitor issue?? Have you tried connecting a different monitor to it and test various reboots with a different monitor?
d4nnyoAuthor Commented:
Thanks for the comments.

LyonJay: I do hear the chime when it boots. I'll check out verbose mode the next time I have the courage to re-boot.

Clioguy: I have checked it with a different screen. Same result.

New results: I had to do some re-installations and re-boots on Tuesday (iPad hassles). The pattern (over four re-boots) was this:

- The Mac Pro  RE-BOOTS to a black screen.
- The Mac COLD BOOTS successfully.

I don't have time to verify this new information with ten boots in a row. But this may signal a change in the pattern. It was consistent across four boots.
At this point I'll have to say Video Card.... can you put your hands on a new one? Or maybe a second hand one from somewhere?
I would have you try a different video card.

If your monitor is going black after a power cycle and not coming on even after changing monitors it sounds as if the signal is not leaving your video card.

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d4nnyoAuthor Commented:
That's a reasonable suggestion. However, here's something new that recently occurred:

- Put the MacPro to sleep
- When I directed it to awaken several hours later, the video flashed up for 1 second
- Then the screen went to black

Could this also be the video card?
I would pull that Video card. I don't know how your cooling system is set up on the card but my quadro FX4500 is a dust magnet, It has like radiator grill fins that clog up with dust.  if i would not have cleaned it scrupulously every 4 or 4 months I am convinced it would have fried. Remove it and thoroughly clean it. In the meantime, Order a new compatible card from a vender with  generous return policy and test it. I would not go chasing firmware before thee chain of easiest to hardest known good is followed. I would also not hurt swapping ports after your original card is thoroughly leaned and also get a new known good cable into play. Then you can look at the ghosty stuff. Do you have access to a walk-in freezer?
d4nnyoAuthor Commented:
Well guys, economic reality will have me live with this for now. I'll save up for a 4870.
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