The Mac Pro First Generation is an Intel Xeon-based workstation computer manufactured by Apple Inc. The first generation model includes the machines from 2006 through 2008.

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Machine won't boot, Graphics card fan running at full speed

My 2009 quad-core MacPro suddenly turned off over night and does not start up anymore.

When I try turning it on the graphics card fan immediately spins at full speed. CD and HDs are being initialized. The other fans are running at normal speed. Logic and CPU board LEDs are turned on.

I'm not getting a chime on startup nor any picture on the screen. I cannot reach the machine via network either, so it does not seem to boot at all.

I tried the usual procedures: PMU Reset, NVRAM reset.

Anyone has an idea what's broken?

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Your post and solution give me great confidence. I have exactly the same issue. When I pulled out my processor tray I could hear the plastic clip/screw and spring rattling. When it rolled out and I googled it I found your post. I cannot believe it. It seems that several owners have had this problem. My one concern is that the northbridge is fried because the sink had been off for a while, and the loss of the chip is really what killed the machine. But this was clearly not the case with yours. Perhaps there is electrical continuity between the fastener points on the sink and the machine knows if it pops off.


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It turned out that it was not the CPU but a broken plastic screw that pressed the northbridge's heat sink against the chip.

After putting new thermal grease on the chip and replacing the broken bolt with a screw and a nut the machine turned on again.

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Look into the LED diagnostics.

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The red light on the processor board is on.


I guess the processor is dead. Is it possible to replace with any stock intel nehalem cpu?


No - for EFI and software update reasons you'd have to put a CPU in that Apple used/supported Processor types vary -- all models in the "Early 2009" line have 45-nm Xeon "Nehalem" processors and some models in the "Mid-2010" line have 32-nm "Westmere" processors and others have 45-nm Xeon "Nehalem" processors like their predecessors. Memory varies as well -- all models in the "Early 2009" line and some models in the "Mid-2010" line support 1066 MHz PC3-8500 DDR3 ECC SDRAM whereas others in the "Mid-2010" line support 1333 MHz PC3-10600 DDR3 ECC SDRAM. See for more information.


I actually meant any *compatible* cpu and not just any nehalem cpu. So when I am getting exactly the same model it should work or do the Apple CPUs differ from the Intel stock cpus?

Could there be any other reason why the processor diagnostic light is on? E. g. cooling (the fans are still spinning tho) or the processor board itself?

Thanks for your help. I really appreciate it.


The CPUs are not custom - but they are of specific generations. Yes - the different diagnostic LEDs represent different issues. Which one are on, or off indicate different problem areas.


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