iMac 2007 not behaving, again!

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Just after installing a software update that required a restart (I guess a kernel or firmware upgrade) our iMac did it again: After the initial chime, it started beeping and it refused to boot up.

In a previous post I mentioned that as three beeps means a RAM memory problem it may well be caused by a non properly seated memory module. So this time I remove the power cable and I opened the memory hood on the bottom of the case. It looked ok but, just in case, I took the memory out and I plugged it in again. It looked to fit well (before and after).

Unfortunately this procedure caused no change on system behavior: After the initial chime the system will beep twice and then it will continue making three beeps until you power it off.

Knocking the unit did not help either. It's time to consider the choice of sending the unit back to Apple. But as I could not do this on a Sunday afternoon I decided to try to learn more about the issue. Googling lead me to some awful stories. I guess I'm glad I'm still using the original memory supplied by Apple.

In some forum messages it was suggested that resetting (or zapping) PRAM could help. Apparently there are certain values that are stored in non-volatile memory, some of them related to the system RAM. The idea is that the RAM is ok but improperly configured then it won't work.

So I did reset the PRAM thing, by holding the four keys Command, Option (labeled as Alt in my keyboard), P and R. Not an easy thing if you want to do that using one hand, so you can use the other hand to power on the computer, as keys need to be pressed before the gray screen appears .

This procedure did help and the computer booted afterwards without a problem. Now I am not sure what to do. If I go to the Apple shop and it is working I'm guess I'll be told the system is fine. If I wait till the problem happens again they may well reset the PRAM and the system will be fine again. The point is: Can I trust this computer? Is this a sign of computer malfunction or is it a software glitch?

Unfortunately I do not know the answer and, even worse, I'm not sure what is the best thing to do next. Having to reset the PRAM every now and then is a minor annoyance if this is all what it is. But failing to get the computer serviced while still it is under guarantee would be foolish too.

Update: Although previous attempts with the Hardware Test software haven't spotted any problem in the past. I tried again as kernel panic messages were happening more often last week. This time I've got a Memory error in a few seconds: Bingo! Now it is time to bring the computer to the Apple shop. Hopefully the root cause of all my trouble is just a bad DRAM SIMM! (the original memory that came from Apple).

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