early mac pro will not boot fans on high

Question

early mac pro will not boot fans on high

My 2006 Mac Pro is usually on all the time. This morning I found it with the fans running high and not responsive. I forced shut down, waited a few minutes, then hit the power button. It immediately went back to the high speed fans but wouldn't boot. Any suggestions on finding out a solution? I've searched the Internet and didn't find answers. Is there a reset button inside the case? I've never been aware of one, but I don't know everything. <grin>

Thanks in advance for any help.

Posted on Jan 31, 2021 9:31 AM

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Answer 1

Top-ranking reply

Grant Bennet-Alder

Level 10

135,775 points

Jan 31, 2021 10:22 AM in response to Golf25Radioman

No fans after power removal? Check or Replace the 3 Volt non-recharging coin cell PRAM backup battery, half-hidden behind the graphics card. The holder is delicate, and breaking the holder will ruin your day. Use a bright light and understand fully before you act.

Anything under 3 Volts is not adequate. A new CR2032 (used in car-key fobs and garage door openers) will measure a bit over the nominal 3 Volts.

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Answer 2

Jan 31, 2021 9:51 AM in response to Golf25Radioman

Reset the SMC on your intel computer:

Desktop computers

Shut down your Mac, then unplug the power cord.
Wait 15 seconds, then plug the power cord back in.
Wait 5 seconds, then press the power button to turn on your Mac.

1a) some Users swear by: press and hold the power-on button for 15 seconds with the power cord removed for a complete power drain.

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Answer 3

Jan 31, 2021 10:15 AM in response to Grant Bennet-Alder

I disconnected the power cord, waited, also pressed pressed the power button while disconnected. Pressed the power button and same thing there. No chime, and fans on high, no booting... Hmmm

Now what???

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Answer 4

Jan 31, 2021 11:03 AM in response to Grant Bennet-Alder

Fans still on high when power button pressed, and no boot still. I am not an expert by any definition, so I have been looking at various places about this issue. Is there a possibility that this is the power supply? There have been some discussions about LEDs inside, etc., but I have not opened the case up yet. I'm in information overload right now.

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Answer 5

Jan 31, 2021 11:27 AM in response to Golf25Radioman

I thought you said no fans.

sorry, I see you said fans on high and I mis-read.

If fans are running, 12 Volt power tends to be just fine. If it responds when you press the power button, 5 Volt power tends to be present.

Yes, there are some diagnostic LEDs inside.

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Answer 6

Jan 31, 2021 11:32 AM in response to Grant Bennet-Alder

I don't want to go throwing parts at a problem (something I learned as a General Motors Technician). Should I get into the case so I can see these LEDs? Or could this be something like a power supply, dead PRAM battery, or ??????

This MacPro is used in my house as my network computer so I have a number of external HDs connected to it for data storage. I am currently mostly using my MacBook Pro in the living room for most of my computer work. But it is imperative that I get the MacPro back up so I can get to my storage. I realize that this old MacPro is "ancient" but it has been doing a great job for what I use it for. I'd like to get it back up, if possible, for a reasonable cost, as quickly as possible.

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Answer 7

Jan 31, 2021 11:44 AM in response to Golf25Radioman

You a technician of any description? that changes everything.

The approved method for this sort of problem is to remove EVERYTHING that is in a slot. Remove (or just slide out) all the hard drives. remove or disconnect the Optical drives. remove all the PCIe cards including the graphics card. Remove all the RAM DIMMs.

Power up.

The power-on light will blink a code to you -- IF and only if the processor is running.

Count the blinks before repeat and report back.

expected answer: the code that says, Processor OK, No RAM at all.

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Answer 8

Jan 31, 2021 11:55 AM in response to Grant Bennet-Alder

I might add one other thing. Last week a winter storm went through here and a lightning strike happened fairly close. It broke out a window in one of the bedrooms - and scared the heck out of me and the animals. My master bedroom TV was in use and the video went away. I have a 42" HD, connected to a TiVo via HDMI. All the TV said was there no signal, which could either mean the HDMI board on the TV or TiVo got a spike. I have another TiVo and TV on the way. The TV is old enough that it wouldn't be worth taking it in for repair. But the MacPro was working way after this lightning event. I don't go into the room where it is but the network storage HD icon was on my MacBook Pro desktop until this morning. That's when I went into the room and found the fans on high and I forced a shut down, and the rest of what I've posted goes on from there.

Could this play into anything in the diagnosis of what is going on now?

Thanks for listening/reading...