This post just made me get out my old 2X 1GHZ Quick Silver from my attic with close to the same issue. fan comes on, no powerlight,red light on system board! I put it in the attic 6 months ago. because i did not want to see it any more😁 i put in a new psu in it (i tested the old one first with a multimeter and it was dead well almost) and i reset the computer. and it worked fine for 2+ weeks. then back to NO START UP😟 so i put in new, ram,hard drive,video card,pram batt,cpu card. With no look😟 so now i have over $300+ in a 7+year old computer that i can get on ebay for way under $150 and it still will not work. so i was very mad at it and i put it in the attic😠 i took it out just today and it turned on🙂 i put os x 10.5 in it played with it a little and turned it off. i will just say 1 thing it is going back in the attic it is not working any more. well i at lest had 1 last time to use it😟 next thing is to get a new system board. i will just get a used QS at a flea market or E-bay for use or for parts.