crwdns2893792:0crwdne2893792:0 Stone ,



Thanks for your replies.

Why I am asking?

It 's not that I am not feeling familiar with such "repairs" or that I do not know much about computer stuff in general, but I always like to hear a second or third opinion.

In this case I am wondering about the 3 beeps while pressing option key during power up of the MBP - according to Apple this indicates "bad banks" of RAM, which I like to interpret as bad RAM modules, not properly fitted modules or - worst case - broken RAM slots.

The question mark indicates - according to Apple - that the boot signature / boot device cannot be found; this might be broken disk, a "dying" disk, a bad cable or - worst case - a faulty controller.

I also assumed to boot from an external drive, but this will only show if the system (hardware) can be booted, but the onboard HDD controller is not involved IMHO and also not the internal cable (so both parts can still be faulty).

So - finally - my question is if somebody knows if the onboard HDD controller is always involved in disks operations (but AFAIK USB disks do have their own controller) and if the 3 beeps are indicating broken slots (most times) or faulty, bad fitted RAM modules.

I can imagine that the system won't boot up because of faulty RAM modules, too.

Regards, Stone