Resolved Unable to reset PRAM

[pl1984]

I have an early 2005 dual processor 2.3GHz PowerMac for which I am unable to reset the PRAM. Specifically this model:

https://everymac.com/systems/apple/powermac_g5/specs/powermac_g5_2.3_dp.html

Due to the system reporting the clock needed to be reset I decided to replace the PRAM battery. Upon doing so the first thing I attempted to do was reset the PRAM (Command-Option-P-R immediately after powering on). The system powers on and starts to do its thing (whatever that is) but it never chimes nor reboots. As long as I hold this key combination down it just sits there doing its thing. If I release the keys the systems boots and appears to run normally.

At first I thought maybe there was a problem with the new battery so I reinstalled the original one. Same problem. Still thinking maybe there was a battery issue I installed a second new one (I bought a package of them). Same problem.

I then decided to start the system into Open Firmware (with Command-Option-O-F) where I issued the following commands (which were successful):

reset-nvram
set-defaults
reset-all​

I then powered down and attempted to reset the PRAM. The problem still exists. I also attempted to reset the SMU which, according to the direction I found, is to unplug the computer for a few minutes and then try again. The problem persists.

I'm unsure if the issue is related to the PRAM battery replacement or existed prior to doing so (as I can't recall the last time I needed to reset the PRAM on this Mac). It's possible it existed beforehand and I just didn't realize it. Aside from not having the boot chime and being able to reset the PRAM the system appears to work fine.

One thing to note: The new batteries have the same part number as the original (LS14250) except the original has a "C" on the end (LS14250C). Before ordering I examined the specifications of the new batteries and they appear to be identical to the original battery...same voltage (3.6v), same amperage rating (1200mA), same brand (Saft), same polarity (installed in the correct direction, positive away from PCI slots), same appearance. The only thing different is the "C" on the end of the original batteries model number. I used a grounded wrist strap when replacing the battery.

While the system is perfectly useable I hate the idea there's something wrong with it and therefore want to correct it. Any ideas?

 

[iTurbo]

Try a different keyboard. I had this happen to me yesterday trying the same thing on an iMac.

 

[pl1984]

Try a different keyboard. I had this happen to me yesterday trying the same thing on an iMac.

Thank you for the advice. I have heard about issues with iMacs and keyboards. Unfortunately it did not resolve the issue I am experiencing.

Additional information: Both keyboards are original Apple keyboards. The keyboard I normally use is the white Apple Pro Keyboard (which, I believe, is the one which ships with the system). The test keyboard I used is the Apple Aluminum Keyboard (the full sized version with numeric keypad). I've had no issues with either. In addition I utilize the USB extender cable Apple shipped with some of their systems. I also performed testing with and without this extender cable as well as testing on both rear USB ports.

 

[XaPHER]

I also attempted to reset the SMU which, according to the direction I found, is to unplug the computer for a few minutes and then try again. The problem persists.

There's a grayish push button on the main board you're supposed to hit after the machine has been unplugged for a few secs. Plugging it back after another 20 seconds should be okay. May be worth it after a battery swap since it does power the smu.

Zapping PRAM is also done by entering the reset-nvram.. sequence in OF on new world machines. So if everything works except cmd-opt-P-R at startup I'm unsure what to say. I'd suggest temporarily unplugging any usb device other than your keyboard (including a non-apple mice) since that doesn't hurt and try again if you really want to.

 

[pl1984]

I wanted to follow up as I discovered the cause of this problem. It ended up being a problem with the RAM slots J11-J14 (inner most slots). They appear to be bad as the system flashes the power light three times when I populate only those slots (J11 and J12 or J13 and J14). If I leave DIMMs in those four slots and populate the remaining ones (J41-J44) the system boots but does not chime. Removing the DIMMs in slots J11-J14 and the system chimes and boots. With this configuration I can also reset the PRAM.

In the end it turns out I have a bad DIMM sockets on the motherboard and, populated with DIMMs, resulted in the systems inability to reset the PRAM.

 

[z970]

I wanted to follow up as I discovered the cause of this problem. It ended up being a problem with the RAM slots J11-J14 (inner most slots). They appear to be bad as the system flashes the power light three times when I populate only those slots (J11 and J12 or J13 and J14). If I leave DIMMs in those four slots and populate the remaining ones (J41-J44) the system boots but does not chime. Removing the DIMMs in slots J11-J14 and the system chimes and boots. With this configuration I can also reset the PRAM.

In the end it turns out I have a bad DIMM sockets on the motherboard and, populated with DIMMs, resulted in the systems inability to reset the PRAM.

My condolences.