I have a Mac Pro (Intel, 2008). Within the last 6 months, a situation with the Mac Pro has occurred twice.
While asleep, or shut down, I press the Power button to start up the Mac Pro leading to the following events:
- the graphics card fan runs at full speed.
- the LED indicators on the RAM cards all light up red.
- the HDD's begin to spin.
- the startup chime does *not* sound.
- the screen does *not* turn on.
- the fan does *not* slow down.
several seconds after pressing the Power button to start up the Mac Pro, it shuts itself down.
- it is not possible to reset the PRAM. (the startup sequence does not proceed far enough to allow this to happen.)
- resetting the system via the reset button on the mother board does not affect the situation.
- replacing the PRAM battery does not necessarily correct the situation.
- removing every HDD, RAM card, PCI card and cable does not correct the situation.
this is what has worked for me.
assuming that the Mac Pro is not powered up:
- unplug the power cable.
- press the Power button for 5 seconds to drain any residual power from the system.
- let the Mac Pro sit idle for 12 to 24 hours. (10 minutes simply doesn't do it!)
- plug the power cable in.
- press the Power button to boot up the Mac Pro.
removing the HDDs, RAM cards, PCI cards and cables may or may not affect your situation.
the first time my Mac Pro booted after this procedure, only 4GB of RAM was recognised by the system. I shut down the Mac, removed and re-inserted the RAM cards and booted the Mac up again. the Mac then recognised all of my RAM (20GB).
hopefully, we'll see a new generation of the Mac Pro this year with *both* firewire and thunderbolt.