Mac Pro tower won't power on. Shuts off 2 seconds after depressing on buttton.

Question

Mac Pro tower won't power on. Shuts off 2 seconds after depressing on buttton.

MAC PRO (Early 2008 model)

Processor: 2 X 2.8 GHz Quad-Core Intel Xeon

Memory: 16 GB 667 MH DDR@ FB-DIMM

Graphics: ATI Radeon HD 4870 512 MB

OS X Yosemite, Version 10.10.3

When I push start button to power on the machine, the indicator light comes on and I can hear the fans start and literally 2 seconds later the machine powers off. I cannot get it to run more than 2 seconds! I have tried disconnecting the power cable, monitor and all other cables from the tower, as well as removing and reinstalling the drives and RAM. all without success. As soon as I attempt to power up the unit, I have the same result: it powers of in 2 seconds. Does anyone have any idea what is wrong and how to fix the problem?

Mac Pro, OS X Yosemite (10.10.3)

Posted on Aug 3, 2015 12:08 PM

Reply

Answer 1

BDAqua

Level 10

239,495 points

Aug 3, 2015 12:14 PM in response to macmillvalley

Ouch, tough to tell, but sounds quite the same as my Mid 2010 Mac Pro, it was the Logic Board gone bad.

Have you checked the CPUs to see of the heatsinks have become loose?

Reply

Answer 2

Aug 3, 2015 8:59 PM in response to BDAqua

The approved method for dealing with situations like this is to disconnect or remove everything that is in a socket or slot and try to get the chime. (If you can't get the chime, you are going nowhere.) The theory behind it is that you are removing everything that could be dragging down power.

Remove:

all peripherals

graphics card

all Hard Drives

all DVD drives

all PCIe cards

all RAM modules

A working Mac powered up in this condition will blink its power light under program control to tell you, "Not enough working RAM to start up." The fans will stay on, and you can measure the 5 Volts and 12 Volts at a DVD-reader Molex connector.

Then power off, add in some working RAM, and look for the chime.

Then add in the graphics card and look for the blinking question mark.

Then add a drive and see if you can get it to boot.

Reply