Silver g4~ once on/off problem please advise

Old g4 silver, OSX 10.4 have had since new, all the bells and whistles, sits in office OFF for months at a time till i need to use it for a job. It turns on fine then, but after on for more than 24 hours, computer is off and refuses to restart. power button lights up then once finger leaves button~ light shuts off~ never starts... until a few days later when (cold cold cold ) again???

i tried removing all accessories, external drives ect, same thing.
zapped p ram

maybe this narrows it down... trying to diagnose the issue i removed all extra boards, ram, cleaned it reinstalled and it still did not turn on... but i noticed it makes a subtle noise when i plug the power cord back into the computer, unplug replug hear something so faint hard to actually notice... changed power cord and same thing.

but a few days later it turns back on and seems lightning fast.

power supply ???

also, sometimes movies played on external hardrive seem to be skipping/jumping... wondereding if these issues were related?

video/graphics card going bad??

if anyone has a suspicion of what they think please let me know

thanks everyone

I am not sure if im going crazy, but random electronic things in my home occasionally seem to not work correctly... then a few days later everything fine again. even remote controls...errrrr (i have witnesses) hheeheheheeh

thanks again

Simply put you gotta ghost!

Seriously as your machine sounds like a MDD, try replacing the PRAM battery as they can cause all sorts of problems in MDD models, particularly as it sits for months at a time with no power on. Does the machine keep date and time okay?

Maybe reconnecting to the power gets enough of a trickle charge back into the battery to enable booting. That faint noise when reconnecting power is pretty standard - things going into stand-by. G5 does it as did MDD 1.25GHz before that.

i must have a ghost.. weird i know... i go to watch a movie in bedroom and tv wont turn on, next night tv turns on... its the story of my life lately.... AGGHH


MDD? not sure whats MDD but i will replace the pram batt... is that the main battery that i notice immediately after opening the machine? or is that the battery that ...."DOES KEEP TIME! YES! still accurate... unlike my laptop..." date wrong everytime i turn it on...

IF NOT same battery where might it be? ill research in the meantime thanks again harryb2448