MacPro 4.1 powers up but that's it! No chime,video etc.

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MacPro 4.1 powers up but that's it! No chime,video etc.

My Mac Pro 4.1 2.26GHz early 2009 if failing to start, by that I mean it will power on OK the fans run and there are no error light. It dosnt chime or display video.

These are the steps taken so far.

Removed all memory chips 8x8Gb and then tested in pairs randomly.

Removed battery and pressed power for 5 seconds with no mains attached.

Swapped graphics card out.

The white power indicator on the power button does not flash just solid light.

One thing I have noticed is the the front processor seems to be totally cold while the rear is warmer. Would a duff CPU stop it booting?

any advise on what else I could try please?

thanks

D

Mac Pro, OS X Mavericks (10.9), Early 2009 A1289

Posted on Feb 13, 2016 1:03 AM

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Answer 1

lllaass

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Feb 13, 2016 1:53 AM in response to dobble

Do the fans work?

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Answer 2

dobble Author

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Feb 13, 2016 2:05 AM in response to lllaass

Yes they work as normal

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Answer 3

Feb 13, 2016 6:18 AM in response to dobble

Check for "wiggly" northbridge chip.

pull out the slide out shelf, locate the nothrbridge in the middle of the processor board, partly hidden under heatsink from the processors, and wiggle it. It needs to be tight enough that its heatsink can be effective.

If it is obviously wiggly, one of the plastic pins that secures it may have given up. If it seems tight it is likely fine -- this problem, if it occurs, is really obvious.

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Answer 4

dobble Author

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Feb 13, 2016 7:40 AM in response to Grant Bennet-Alder

Thanks Grant, I will try this later on and report back.

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Answer 5

dobble Author

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Feb 14, 2016 4:32 AM in response to dobble

Hi Grant, Ive checked the one rivet and that's intact, should I check the other also, would this be enough to prevent the Mac from booting If it were at fault?

the 5v light comes on when pressing the test button, when it's powered on and pressed again the psu power light is green and the 5v yellow.

diagnostics lights are all green.

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Answer 6

Feb 14, 2016 6:14 AM in response to dobble

The test is a very primitive, brute force test. Attempt to wiggle the part around by its heatsink.

If it seems pretty solid, you do not have this issue.

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Answer 7

dobble Author

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Feb 14, 2016 10:44 AM in response to Grant Bennet-Alder

OK so it looked fine bput, I thought I'd remove the heat sink and check the other plastic clip, I discovered that one had broken with one side of the tiny little lug missing!

I therefore replaced both clips with machine screws and nuts. I reseated with thermal paste. Whpile doing this I also reseated both CPUs.

I then re-tested and exactly the same issue, no chime, video or hdd activity. I also note that the keyboard caps light does not come on when pressed.

I'm worried now that it's of to the recyclers for the mp 😟

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Answer 8

Feb 14, 2016 2:36 PM in response to dobble

Did you check the battery for about 3Volts in hand?

Do you have an LED lit for Standby Power when AC is present?

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Answer 9

dobble Author

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Feb 14, 2016 2:40 PM in response to Grant Bennet-Alder

I'm not sure what you mean by in hand? Yes I have an amber light when ac is present, the CPU LEDs flash when powering up once and also as power is removed, these are all to be expected I believe.

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Answer 10

Feb 14, 2016 2:50 PM in response to dobble

3 Volts must be manufactured by the power supply as "Standby Power" even with your Mac off, or you cannot power up. But this standby power interferes with accurate measurement of the Backup Battery "in circuit".

The more accurate way to measure the battery voltage is to remove it from the circuit and place it in your hand to measure it.

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