[cbell]

My G5 (duel 2ghz) is acting stange. When I start it up, nothing happens. I find I have to restart 2 or 3 times before the disk will boot. Any ideas as to what might be happening?

Thanks in advance.

[phantomac]

Nothing as in "the screen stays black" or nothing as in "there's not a single sound from the machine".

[cbell]

The screen stays black, and I can't hear the hard drive operate. It just sits, idol, but the power lights are on and the fans are running.

[yusung]

How long did you wait before pressing the on button again? Your G5 is performing a memory check when you start it up that can take a little bit of time. I also have a dual 2GHz machine with 1 GB RAM. It has a delay of from 5 to 10 seconds for its RAM check. If you have more memory, it will take longer. During this time, the machine behaves as if nothing is happenning at all.

Yu Sung

[Turnpike]

This is very similar to an issue that just cropped up on my fairly troubled refurb 1.8. Nothing happens (screen stays black... power light is on, and I can feel air coming out the back)... It can stay like that for several minutes, I haven't tried longer... only 512 MB RAM

[Eugene Fields]

Originally posted by cbell:
My G5 (duel 2ghz) is acting stange. When I start it up, nothing happens. I find I have to restart 2 or 3 times before the disk will boot. Any ideas as to what might be happening?

Thanks in advance.

Have you tried

Resetting the PMU on the Logic Board

The PMU (Power Management Unit) is a microcontroller chip that controls all power functions for this computer. The PMU is a computer within a computer. Its function is to:
• tell the computer to turn on, turn off, sleep, wake, idle, etc.
• manage system resets from various commands.
• maintain parameter RAM (PRAM).
• manage the real-time clock.

Important: Be very careful when handling the logic board. The PMU is very sensitive and touching the circuitry on the logic board can cause the PMU to crash. If the PMU crashes and is not reset, the battery life goes from about five years to about two days.

Note: For the location of the PMU reset button on a G5, see the Space under the lower memory Bank towards the middle of the chips, Small eraser size button, Labeled PMU.

When you have a computer that fails to power up, follow this procedure before replacing any modules:

1. Disconnect the power cord and check the battery in the battery holder. The battery should read 3.3 to 3.7 volts. If the battery is bad, replace it, wait ten seconds, and then proceed to step 2. If the battery is good, go directly to step 2.

2. Press the PMU reset button once and then proceed to step 3. Do not press the PMU reset button a second time because it could crash the PMU chip.

3. Wait ten seconds before connecting the power cord and powering on the computer. If the computer does not power on, there is something else wrong with it; refer to the “System” section of “Symptom Charts” in this chapter.

Note: The above procedure resets the computer’s PRAM. After resetting the PMU, be sure to reset the time, date, and other system parameter settings.