Q: Mac Pro 5.1 won't power up

Run AHT (Apple Hardware Test)

https://support.apple.com/en-us/HT201257

macjack  the computer does not even turn on to get the Chime so Apple hardware test can't be run

  have you disconnected all external connections except, keyboard and mouse, and power and remove all internal HD sleds and PCLe cards including graphics card?

If you open side cover are any diagnostic light lit on logic board or by memory sticks?

Check the voltage of the coin battery on the logic board. It should be about 3 volts.

There would be possibility that Power Supply Unit is something wrong. Take it to authorised Apple centre or make Genius Bar appointment to tell them about your problem.

Or get Mac Pro5,1 power supply unit at ebay and replace with it by yourself.

http://www.ebay.com/sch/i.html?_from=R40&_trksid=p2051541.m570.l1313.TR0.TRC0.H0 .Xmac+pro+5%2C1+power+supply+unit.TRS0&_…

in some rare case this might help:

- remove the power cord

- wait 5 to 10 seconds

- reconnect power cord

- push pwr button

if it helps:

- cheer!

if it didnt help:

- curses! or ask Illaas, macjack, kas-k 

greetings from germany

Chris

Christian Stueben  for info the poster said:  "I have reset the SMC but no go"

Reset the System Management Controller (SMC) on your Mac - Apple Support

Resetting the SMC is what you recommended so the poster already tried that.

Christian Stueben wrote:

 

in some rare case this might help:

 

- remove the power cord

- wait 5 to 10 seconds

- reconnect power cord

- push pwr button

 

if it helps:

- cheer!

if it didnt help:

- curses! or ask Illaas, macjack, kas-k 

 

greetings from germany

Chris

David Dwight wrote:

 

my Mac Pro 5.1 (six core - 2012 vintage) will not power up...

push the power button and it clicks but no boot, no fans come on, no lights stay on, no chime, ...

Been there, done that with a 5,1 2010 Mac Pro. What sometimes worked, at least for a while, was to leave it unplugged for at least an hour, and if it booted at all, it would run fine.

The Genius Bar evaluation was a failing button battery but they'd ordered a power supply just in case so I asked them to install that too since the Mac was reaching EOL. After installing both, they agreed the PS was going too. That fixed the problem.

This exact same situation has happened to me today. Mac Pro worked just fine last night. Went to boot it up today and nothing. Exact same situation as the OP stated. I replaced the battery for the mother board backup. Nothing has changed hardware wise. The only recent things to happen was the latest Mac OS X 10.11.5 update and the new Nvidia Web Drivers for my aftermarket card. I reinstalled the old (known working) ATI video card and same situation.

Question, could this be an issue related to the last El Capitan update and not a hardware issue? I really don't want to drop $250+ on a new Power Supply only to not have my Mac Pro work.

I have exactly a similar 2012 era 6 Core Mac pro.

I get nothing when I press the power button. Just a click. No fans, no chime, just as described. Please Help.

Mike R

Try unplugging it from power for at least an hour and maybe overnight. While that isn't a solution, it may point to the PS, as it did on mine.

I replaced the battery for the mother board backup.

that is a good thing to try for a Mac that has been moved or may have been off main AC power.

Ok, replaced the motherboard small watch battery. No good. Ended up buying a new replacement power supply. Was a chore to install it but not too difficult. Also gave me a chance to clean out all the dust and such. Plugged it in and fired right up.

So in this situation, the power supply died. That was my solution. I tired all the other suggestions.

Regards,

Mike