Mac Pro power issue

[Mackilroy]

Earlier today I was poking around inside my Mac Pro while waiting for my 4890. I decided to pull out the optical drive bay and see if I could remove the power cords plugged into the PSU. Only took out one, but I put it back in, made sure all four cords were seated, and tried turning it on.

All I get is a clicking noise coming from around where the power cord on the back is. A 'click-click-click' that continues until I unplug the cord. I don't get a startup chime or anything else. Before today the machine worked perfectly. Any ideas on what I've done wrong and how to fix it? Any other information that I need to provide?

 

[gugucom]

It sounds as if you have a pre 2009 MP. In these machines the separate power cable bundles are actually connected by plugs under the fan unit that sits between the PSU and the ODD bay. Check for any loose connectors.

 

[Mackilroy]

I do - it's a 2006 model. I thought I'd checked them all before, but will do so again.

 

[Mackilroy]

No luck, everything feels properly connected.

 

[nanofrog]

Did you try the PSU "bundle" (large connector) between the optical carrier and the back case panel?

That rapid clicking acts like the second relay (there's another that engages when the power cord is plugged into the back, and supplies the power that's used to activate the system. It goes to the logic board, to the front switch, and back to the logic board). That switch is getting power.

If it's not a loose connection, it's likely the PSU (it's unable to generate adequate current to operate the system). If the PSU checks out, then the logic board becomes suspect.

 

[akadmon]

This may be a long shot, but boot up with the side panel open and check if any of the lights on the riser cards stay on. They should blink once and then all go off. If they don't blink, you're getting no power. If one or more stays on, one (or more) RAM sticks got unseated when you were jostling your machine around. This happened to me recently when I was installing my new 4870.

 

[Mackilroy]

No lights of any kind come on. I've been working on it with my father though, and we think we've figured it out - when the connectors going into the PSU look flush, it doesn't necessarily mean they are. I can't check the progress now but I'll find out in a couple hours.

 

[Mackilroy]

Okay my dad figured that was it. Tried everything and it works. Guess I should check them more closely next time.

 

[akadmon]

You've got one cool dad! I have to teach mine every Sunday how to connect to the internet, use Skype and check his Fidelity account balance.

 

[Mackilroy]

Heh, mine's an engineer so he's used to figuring things out. Good for me!