problems booting old (2009) iMac
My late 2009 iMac (i7, 16 GB RAM, OS Yosemite) suddenly shut down and "rebooted" - but only gives me a blank black (not grey) screen. I can hear the re-boot chime and hear the hard drive running, but that's it.
I tried resetting SMC, tried restarting in recovery mode - no luck.
Then I tried resetting PRAM and voila it worked - BUT only for a couple of hours. Then it shut down spontaneously and rebooted to nothingness. This time resetting PRAM doesn't work.
Any idea what the problem is? I don't want to take it in for a repair if the likely problem is expensive to fix, but would take it in if it's only a couple of hundred dollars.
I know I'm due for a new desktop, but it'd be great if I could wait for Skylake chips.
Thanks for any suggestions...
(BTW - fortunately I had full backup. While desktop is down I'm using my 12" MacBook for everything crucial, and have been pleasantly surprised at how well it performs.