Mac Pro 5.1 no chime, no boot... but after 10 hours disconnected to power

[Joerg66]

HI all.

Once again the (obviously) very common NO BOOT, NO CHIME problem. I'm running a Mid 2010 Westmere 2.4 8Core with 32RAM, original ATI, Crucial SSD (boot drive), 2 WD 1TB Drives. Additional PCI Card from Avid (ProTools HD Native) for Music Production, 32 GB 1033 RAM, 27"Apple Display

So, did all the Tests from the book, all Diagnostic LED tests,... the whole novel. Since I had a similar problem a half year ago and it came down to bad RAM, I left the machine now with the two newest 4GB RAM, the SSD and just the graphic card (no Audio PCI, no external Drives, USB, etc ..!) DISCONNECTED FROM POWER over night,... so to say a very long SMC Reset,... and I could boot it ONCE. After another restart, same problem as before... all Fans running, LED Diagnostics ok, but no chime, not going further.
Did the same thing next night, and again, could boot without problem (reseted nVRAM this time) ... and again, after restart.... no boot, no chime.

Also replaced the RAM Battery (2032 3V). I have no effin idea anymore. Wahy would it boot after hours unplugged from power. And then only once???

Any HELP is highly appreciated!

One thing to mention: when I start without any RAM in sockets, the (white) power light in front is supposed to blink, indicating not enough RAM. It does NOT do that, light stays on steady

 

[thats all folks]

what would change after hours of being off is that every bit of it would cool back down to room temperature. that could mean a solder point, connector or component that fails when heated a little. as to being unplugged, even off, there is a little power consumption going on, a little bit of heating. maybe the power supply then.

are you leaving it on after booting? trying to do anything with it?

 

[Joerg66]

no, I leave it on for a few minutes... just to check on all fans and if anything changes. but than I shut it down with holding the power button and unplug power cable again.

 

[thats all folks]

is there a reason you aren't doing a normal shut down? what I'm wondering is, would the computer die quickly once it warms up fully or will it stay up without issue?

 

[Joerg66]

The reason for "no normal" shutdown is... it never booted. I can not shut it down any other way. No chime, no monitor. After this two boots it stayed up and worked fine... for the 10-15 minutes I checked Wifi, disk utility, etc.

 

[thats all folks]

hmm. sounds bad. I'd speculate the power supply but that is only a guess. you mentioned having a similar experience before with RAM. it would be a surprising bit of bad luck that you would have even more RAM go bad in the same way. and RAM shouldn't cause it to not post at all.

 

[Joerg66]

Yeah.. it must be a power or heating issue.... otherwise it would make no sense that the machine runs flawlessly after a few hours unplugged.... until you restart. NO logic in this.

 

[h9826790]

I also guess it may be PSU related. If overheat preventing the boot, the machine most likely will auto shutdown at some stage.

On the other hand, a failing PSU may be sometimes hard to "click", but once started, it possible to working without issue.

 

[arash99]

hi did you find the solution for this issue?

 

[Frank DiMaulo]

Same situation here... would like to know if solution found. I already replaced the backplane board, no change. Next ill try changing the PSU then the processor board.

 

[indrek]

Hi, any news, what went bad? CPU tray, backplane board? Same issue here...