Macbook struggles to boot up, takes several attempts

Hello,

My Macbook (2,1) has been going strong for a good 4 years now. It has a 1 year old hard drive and brand new battery. Recently it has suffered from a new problem. It takes several tries to boot up- several meaning anywhere from 1 to 15 attempts, most often somewhere in the middle.

This does not appear to be a power issue. The computer shows signs of life on every attempt: the disk drive will make noises, the power indicator light will be lit, and I may or may not be able to hear the fans and/or the hard drive. However the display shows nothing and all I can do is turn it off and repeat. The computer often sounds very dead on the first try, and after a few power cycles I can hear it getting closer and closer before it finally manages to boot. There is sometimes a startup tone, usually not. Sometimes it will begin to boot but then revert to this unusable state shortly afterwards- but in this case it almost always boots successfully on the next try. Once the computer is warmed up it will run flawlessly for hours on end, and rebooting is no longer a problem until I've left it off for a period of time.

My gut is that this is a logic board issue and that the only solution is to replace it. But I'd love to hear any input from anybody who has experienced this sort of thing.