will not recognize optical drive or extra hdd's

ill make it quick and simple had a problem with my g4 mdd not starting up properly, i would have to unplug from power outlet for it to start again , took psu to electronics repair guy , he replaced a capacitor ... worked fine for 2 days then again, i was about to get fed up and this on day i turned off my g4 with power button rather than thru finder shutdown menu , and voila it started normaly with button , i tried this several times and it didnt bother me any mor , recently changed memory and did it again, i reset with buton on MB and went on without prob , my issue now is after some time after first issue "power up" my g4 didnt wanna recognize my extra hdd's inside it , i have 4 hdd's inside it not to include the 2 optical drives , one a duperdrive dual layer and one a normal superdrive, ok after it didnt wanna recognize my 2 extra hdd's it started not recognizing my cd=roms ... what can it be , should i just quit fiddling with it and sell it on ebay ? its kinda heart breaking for me it been with me for a long time and its been wonderfull to me can someone give me some advice as how to fix this , apple suppor told me to buy a mb 499.98 thats moe than the g4 is worth :( plz advize , thx in advance