オリジナル投稿者： oldturkey03 ,
YellowStickie, see if this helps to narrow it down a bit. I am not a Mac person, just a hardware tinkerer with a few manuals ;-). Hopefully this will keep you busy until the Mac Guru's get to your question :) " Power-On Self Test: RAM and Processor Verification A power-on self test in the computer’s ROM automatically runs whenever the computer is started up after being fully shut down (the test does not run if the computer is only restarted). If the test detects a problem, the status LED located above the power button on the front of the computer will flash in the following ways*: 1 Flash: No RAM is installed or detected. 2 Flashes: Incompatible RAM types are installed or RAM installed in wrong slots. 3 Flashes: No RAM banks passed memory testing. 4 Flashes: No good boot images are detected in the boot ROM (and/or there is a bad sys config block). 5 Flashes: The processor is not usable. * Note: The status LED lights up when the power button is depressed at startup. Do not count this light as one of the diagnostic flashes. Diagnostic LEDs Power Mac G5 (Late 2005) logic boards include a set of LEDs to help service providers troubleshoot the computers. The LEDs are located to the left of the top bank of DIMM slots. [image|218167|align=left] Power-on LED illuminates when power button is pressed and fans spin continuously but there is no boot tone or video Reseat video card. (Make sure video card is fully inserted in connector and end of card is secured by the connector latch.) For video cards that require power cables, check that they are connected. Verify speaker cable is fully seated. Reset logic board. Refer to “Resetting the Logic Board” in this chapter. Check diagnostic LED 1 and LED 6 for processor connection Replace processor Replace logic board Power-on LED illuminates when power button is pressed, fans spin, and boot tone chimes, but there is no video Reseat video card. (Make sure video card is fully inserted in connector and end of card is secured by the connector latch.) For NVIDIA Quadro FX 4500 graphics card, check that power cord for card is connected. Reset PRAM (restart computer while holding down Command-Option-P-R keys until second boot tone chimes) Reset logic board. Refer to “Resetting the Logic Board” in this chapter. Replace video card Replace logic board I posted a service manual to the device page. Check [http://www.ifixit.com/Device/Power_Mac_G5_A1047?revisionid=HEAD|on here] under Support documents. Have to tell you I love the looks of the G5, my kind of machine :-)Hope this helps, good luck.