05-08-2011, 03:56 AM

I just tried upgrading my imac memory from (4) 2gb modules to (4) 4gb modules. The new ones are Samsung 4gb PC3-10600S DDR3-1333Mhz 204-pin SO-DIMM. iMac is 3.33 core duo.

The old ones were 2 different manufactures of memory in the Apple-supplied memory: 2gb PC3-8500 DDR3 1066Mhz....

According to the Apple support site (and a phone call to apple support) the 1333 memory should work, so that's what I bought.

When I install the cards and turn on the machine, within about 1 second I get a beep that occurs every 4-5 seconds. I let it go and it did it more than 9 times in a row. I had looked to see if this was a diagnostic signal, but it doesn't seem to match up.

I took the new memory out; reseated it to make sure it was tight; restarted - same beep.

I reinserted my old memory, and am back up and running.

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Can anyone comment on this issue? I spent about 90 minutes looking around on the web and could not reach a conclusion.

Seems possible that:
a) One of the memory cards is bad
b) the 10600 / 1333 is not really compatible with the HW despite 3 sources that say it should be
c) I'm lucky smoke didn't come out of my computer

Thanks for any insight or help you can give~!

Flypaper

05-08-2011, 06:49 AM

Try the new sticks one at a time to determine if/which stick(s) is bad.
If all pass one at a time, then try 2 at a time.

You may have to try multiple scenarios - it could be that all the sticks are good and one slot is not working with the 4GB.

05-08-2011, 08:19 PM

Not saying Apple gave you bad info.... but there have been several folks who used the 1333 MHz modules in place of the 1066 MHz type and ran into difficulties. The faster modules are not going to make a difference even if they do work. Use the exact modules that Apple supplied with the machine and you'll be fine.

05-09-2011, 10:09 PM

So after much dorking around:

a) In was able to get 2 of the 4 - 4gb memory cards to work - but *only* if they were in the "Front" slots (front=toward screen). Booted up with 1333mhz.

b) If I added the other 2 cards to the back pair, no dice. 5-second beeeep.

c) I put 2 of the old 2-gb cards in the back, in combination with (a) above, and guess what? It booted up just fine with a total of 12gb. Speed: 1066. (The memory and/or board dials the 1333 cards down to the speed of the slowest card).

d) I swapped the different 4gb cards around with exactly the same results.
e) It would not boot with just 1 card of memory in any slot, regardless of size.

Here's an apple link to the Beep tones:
iMac (Mid 2007) and later models: About startup tones

Cheers.