Mac Pro 2008 Won't turn on

[cbt3]

So I have a Mac Pro 3,1 it has been off for several weeks since I upgraded to a newer system, and I was keeping around as a backup, also it has several HDDs in it. I went to turn it on today and to my dismay, when I hit the power button, I hear a click come from the power supply, the usual noise, and then a few seconds later it clicks off. I cannot find anything online about this,

the only thing I could fine was here

https://support.apple.com/kb/TS1367

which let me to try to reset the SMC here

http://support.apple.com/kb/HT3964

which did nothing, I had already done those steps and tried different cables. I am totally at a loss here, and Apple Car expired on this machine over a year ago, does anyone know whats going on?

 

[Mactrunk]

Hard to diagnose from afar.
I had a similar problem, but in my case it seemed to be temperature related.
I replaced the power supply and all is well.

 

[cbt3]

Hard to diagnose from afar.
I had a similar problem, but in my case it seemed to be temperature related.
I replaced the power supply and all is well.

I was thinking it was the power supply, but how do you replace the powersupply on a Mac Pro?, it seems built into the chassis?

 

[cbt3]

And I am looking online, $300 for a powersupply? that seems a bit pricey!
Is it possible it could be the battery in the motherboard? I really can't think of anything else to do to troubleshoot this, like what other diagnosis steps could I try? It just flat out is not turning on?

 

[phpmaven]

I would suspect a failed HDD or a card that needs to be reseated. I would take it out side and blow all the dust out and then pull out any PCI cards and reseat them. Also pull out all of the HDDs and try to just boot off a CD.

It's amazing how many non-booting PCs I brought back to life just by pulling cards out and reseating them, or even just pressing down on components on the motherboard.