Temperamental Mac Pro: Will start; then won't start; then will start etc...

[atlanticza]

I tried to switch it on this morning. Nothing. No noise. No fan and no power light. It's as if this Mac is not connected to a power source at all. But try to start it up a number of hours later, it works as if nothing had happened.

This bizarre behaviour has happened a number of times now over the past week. (And I have reset the SMC but to no avail.)

It can't be the PSU.

I'd appreciate any ideas.

 

[odinsride]

Have you tried unplugging all usb and peripheral devices other than mouse and keyboard? Had a similar issue with my mac pro and narrowed it down to the monoprice usb hub I was using.

 

[atlanticza]

Yes, I went through that procedure when resetting the SMC. No difference, alas. (Maybe it's not an early riser!)

 

[shardey]

Have you tried a new power cable?

Have you tried switching outlets?

What happens if you leave your computer on where it doesn't turn off, let's say for 3 days?

 

[Darth.Titan]

Out of curiosity, how have you determined that it can't be the PSU? That's exactly what it sounds like to me.

 

[nanofrog]

Out of curiosity, how have you determined that it can't be the PSU? That's exactly what it sounds like to me.

It's certainly suspect from the described behavior.

 

[atlanticza]

Out of curiosity, how have you determined that it can't be the PSU? That's exactly what it sounds like to me.

Maybe I'm being ignorant, but I assumed that once the PSU is "blown", it stays that way.

 

[atlanticza]

Have you tried a new power cable?

Have you tried switching outlets?

What happens if you leave your computer on where it doesn't turn off, let's say for 3 days?

I have a number of devices working off the same outlet, and they are fine. As for leaving it on, there has been one occasion where it would not wake up from sleep mode - just remained somnambulant so I held the power button down until it switched off.

 

[erictooth]

Out of curiosity, how have you determined that it can't be the PSU? That's exactly what it sounds like to me.

Agreed, I think it's very likely the PSU.

 

[gnasher729]

I tried to switch it on this morning. Nothing. No noise. No fan and no power light. It's as if this Mac is not connected to a power source at all. But try to start it up a number of hours later, it works as if nothing had happened.

My nephew had the same problem with a PC. Turned out to be the power button on the front of the computer. Try setting System Preferences so it turns itself on say 8am every morning.