Is my iMac RAM incompatible?

March 4, 2012 10:26 PM

I installed new RAM for my 2007-era iMac last week, and for a few days everything went swimmingly. Then the loud beeping started...

I previously had two 1GB RAM chips in the memory slots, and I bought two 2GB chips. So I doubled my RAM from 2GB to 4GB. Easy as pie to switch out, and when I booted up with the new RAM, it started as normal and showed that my RAM had indeed doubled to 4GB. Multitasking was indeed snappier and performance was much better.

That lasted a few days, and then suddenly, this morning, it stopped being good. Firefox froze up, and then every other program, and even Force Quit didn't work. So I rebooted and got the loud beeps, which (I already checked this out) means that the RAM is bad or simply not working for some reason. It will boot up, but freezes after a short time.

I checked the Apple website for the correct type of RAM I needed to upgrade, and when I bought it, the chips had all the specifications I needed: (PC-2 SDRAM 667Mhz, etc.) They were from a brand I haven't heard of before, and the cheapest option, but I didn't think this would be a problem. Is there bad RAM out there?

The bigger question is: why would the RAM suddenly "go bad"? I can understand if the RAM chips I bought were the wrong ones, incompatible with the iMac, but for two full days the computer worked fine. Better than fine. The only thing I can think of (and I can't actually check because I'm at work) is that I was downloading a few large files overnight and my harddrive might be close to full...could this be related? (BTW, it's obviously not a young computer, and has seen almost daily use for the past for almost five years, so it may in its twilight years. That is, about to die, and this could be a symptom.)

Should I just admit defeat and put those 1GB chips back in?

Any advice would be greatly appreciated.

posted by zardoz to computers & internet (12 answers total)

Putting the 1GB chips back in is not admitting defeat - it's the first step in diagnosing the problem. If it works fine, maybe the new RAM was subpar and you should return it, if possible. If you still get the same problems, it might be another component (logic board?), maybe completely unrelated and coincidental.
posted by WasabiFlux at 10:36 PM on March 4, 2012

Have you tried running a memory testing utility like MemTest86 or MemTest86+? You can download an ISO disk image, burn it to a CD, and boot the utility off of that.
posted by Hither at 10:39 PM on March 4, 2012

You should probably futz with the RAM chips, if only to narrow down your issue.

First, I'd make sure that the problem isn't just loose RAM. Open up the memory compartment, take out the new RAM, and put them right back in, making sure they're secure and tight. Then try booting up, and see if it works. If so, great!

If that doesn't work, then try putting the 1GB chips back in, and see if that helps. If it does, then you know the 2GB chips are the problem, call up wherever you bought them from and arrange for a refund.

If both of those don't work, you can try other things to narrow down the problem further. I doubt a full disk would prevent booting, but you could try booting from the CD that came with your computer if you want to be sure.
posted by vasi at 10:39 PM on March 4, 2012

Macs are notoriously intolerant of dodge RAM. Modules that would work with no problems in a PC will cause a Mac to choke. When in doubt, the safest bet is to buy brand-name RAM. If there are some marginal spots on these modules, then a couple of days of burn-in could've been all they needed to flip from 'almost good enough' to 'not working.'
posted by 1adam12 at 12:44 AM on March 5, 2012

Ok, back home and...things are actually worse than I expected. I replaced my new RAM with my old RAM, and the beeps have stopped. But still have problems, and I don't know if the bad (?) RAM really made some permanent damage.

I turn on the iMac and it boots in OSX and displays my wallpaper (of my cat). I can also move the cursor around. That's it; no icons no taskbar, nothing. Just the stupid cat wallpaper. I reboot and choose my Windows partition, and Windows starts to boot up, but then does a checkdisk that I can't cancel ("press any key to cancel" but the keyboard doesn't seem to work.) It then reboots back to my cat.

I had one more option, to boot from my backup drive. Which is what I'm using now and what I'm typing in: my Time Machine backup. Which seems to be the equivalent of driving around on a few spare tires--not an optimum long term solution.

I'm currently verifying my hard disk with the Disk Utility. What else can I do? It really looks like this thing is toast, but it does boot up into my desktop, granted, everything is gone but it is booting up.

Any suggestions?
posted by zardoz at 2:17 AM on March 5, 2012

Try doing a PRAM reset
posted by Lanark at 4:41 AM on March 5, 2012

Replacing memory would not affect the operating system in the manner you are describing, even if you had faulty memory for a time. This sounds, as you suspect, like a hard drive issue, unrelated to the memory sticks you were using - and the Windows chkdsk is essentially backing up the same theory.

I would turn the machine off, stop booting it immediately, and replace the hard drive. You may be able to salvage data from it as an external drive, via a cable, for a few more boots, but leaving it powered on or booting it up will exacerbate the problem, if you have a drive that is eating itself.
posted by ellF at 4:41 AM on March 5, 2012

Sounds like a mix of issues. A bad hard drive would not cause the beeping. Faulty RAM wouldn't mess up the hard drive or OS (as ellF has already said).

Send the RAM back, buy a new HDD (verifying the disk was a good choice to see if that really is the issue), and restore from backup.
posted by FrereKhan at 5:04 AM on March 5, 2012

A bad hard drive would not cause the beeping.

I'm not sure about that. I've experienced the big beeps at bootup with a bad HD. The RAM was fine, but the communication between it and the HD may not have been good. (It seems to have been a software issue.)

Not pretending to be an expert in any way, just chucking in some anecdata from a machine that's a bit newer than but similar to your own.
posted by Wolof at 5:16 AM on March 5, 2012

Ok, I booted it up in safe mode (held down the shift key while booting), and then verified the disk in Disk Utility. It gave me a nice green sentence that said no problem. I ran iDefrag just to be safe, then rebooted, and now it's back.

So I guess it's a coincidence that the hard drive is acting screwy after putting in that RAM? I'll try to put that new RAM back in, but will wait just a bit. Could be that this hard drive is in the final countdown.

Anyway, thanks all for your help!
posted by zardoz at 5:37 AM on March 5, 2012

FYI, I upgraded the RAM in my 2007 iMac a few years ago -- like you, I went from the two default 1GB chips to two 2GB chips of name brand RAM from New Egg. Things mostly worked fine, but my Mac froze up reliably when I tried to play WoW. I ran some sort of memory-test utility (possibly MemTest86, but I can't be sure) and it faulted the RAM. I returned the chips for two replacements, and all problems were solved.

Point is, yes, bad RAM is out there, and even the quality manufacturers sometimes put out bad chips.
posted by BurntHombre at 6:37 AM on March 5, 2012

RAM goes bad all the time, at any time. Most places will exchange it for you without any questions because it happens so often. DON’T use bad RAM. You can write corrupt files to the drive.
posted by bongo_x at 11:33 AM on March 5, 2012