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Mike the Mac Medic
Mike the Mac Medic, Mac Support Specialist
Category: Mac
Satisfied Customers: 8996
Experience:  Over 20 years IT experience with Apple computers in publishing, marketing and design.
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My mid 2007 iMac will not read new 2GB memory module in slot

Resolved Question:

My mid 2007 iMac will not read new 2GB memory module in slot DIMM/1. I have installed 2 new 2GB modules (slot 0 & slot 1) in place of previous 1GB module in slot 0. Slot 0 can read either of the 2GB modules but slot 1 can read neither of them! It does, however, read the original 1GB module (from slot 0). How can this be?
Submitted: 2 years ago.
Category: Mac
Expert:  Mike the Mac Medic replied 2 years ago.
Mike the Mac Medic :

Please go to the Apple logo at the upper left of your computer screen to About This Mac and give me this information:
The exact system Version (listed right under Mac OS X)
Processor
Memory

JACUSTOMER-mxiu04n9- :

Version 10.6.8

JACUSTOMER-mxiu04n9- :

Processor: 2.4 GHz Intel Core 2 Duo

JACUSTOMER-mxiu04n9- :

Memory: 2 GB 667 MHz DDR2 SDRAM (although 4 GB is actually installed)

JACUSTOMER-mxiu04n9- :

Memory Slots:

ECC: Disabled

BANK 0/DIMM0:

Size: 2 GB
Type: DDR2 SDRAM
Speed: 667 MHz
Status: OK
Manufacturer: 0x7F7F7F7F7F9B0000
Part Number: 0x4354324732533636374D2E4D3136464D0000
Serial Number: 0x00000000

BANK 1/DIMM1:

Size: Empty
Type: Empty
Speed: Empty
Status: Empty
Manufacturer: Empty
Part Number: Empty
Serial Number: Empty

JACUSTOMER-mxiu04n9- :

NB: BANK 1/DIMM1 has the same type of memory module as BANK 0/DIMM0

Mike the Mac Medic :

What is the serial number of the iMac?

Customer:

Model Name: iMac
Model Identifier: iMac7,1
Processor Name: Intel Core 2 Duo
Processor Speed: 2.4 GHz
Number Of Processors: 1
Total Number Of Cores: 2
L2 Cache: 4 MB
Memory: 2 GB
Bus Speed: 800 MHz
Boot ROM Version: IM71.007A.B03
SMC Version (system): 1.20f4
Serial Number (system): W87418EHX86
Hardware UUID: 00000000-0000-1000-8000-001B63ACF0FD

Mike the Mac Medic :

OK it should take the 4 GB either the RAM is not good or compatible which is usually the case so I suggest you try this and if it persists replace the memory:

Mike the Mac Medic :

Resetting the SMC & PRAM for Mac Pro, Intel-based iMac, Intel-based Mac mini, or Intel-based Xserve
1. Shut down the computer.
2. Unplug the computer's power cord.
3. Wait fifteen seconds.
4. Attach the computer's power cord.
5. Wait five seconds, then press the power button to turn on the computer.
6. Press and hold the Command-Option-P-R keys before the gray screen appears.
7. Hold the keys down until the computer restarts.
8. Release the keys.

Customer:

OK, tried that but no change. If both modules work in DIMM/0, does that not mean that the memory is OK?

Mike the Mac Medic :

Not necessarily did you blow out all the dust with an air can?

Customer:

No I didn't, but the 1GB module originally from DIMM/0 works OK in DIMM/1. It's just the 2GB that doesn't show up. Is there some sort of difference between DIMM/0 & DIMM/1?

Customer:

The memory is from Crucial and is "4GB(2x2GB) DDR2-667 SODIMM MAC" & "CT2C2G2S667MCEU".

Mike the Mac Medic :

This is the one you should be using:

Mike the Mac Medic :

CT3265291

Customer:

OK. I'll go back to Crucial and try that. Thank you.

Mike the Mac Medic :

OK let me know

Customer:

I'm still waiting for a response from Crucial. If and when I hear from them and get the memory modules exchanged etc. I will give feedback. The reference you supplied (CT3265291) cannot be found on the UK site, only the US one, so I don't know if that's a problem. Anyway I'll let you know if / when I hear anything.

Mike the Mac Medic :

OK

Expert:  Mike the Mac Medic replied 2 years ago.
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Customer: replied 2 years ago.

OK, so I emailed Crucial and they responded that the ref "CT3265291" is a US ref and is equivalent to the one I ordered, which was "CT3331873" on the UK site (the number I gave you previously was from a sticker on the box and is obviously not the kit ref - sorry). However, on the Crucial website there are two ways of searching for memory for my iMac: If I call it "iMac (Mid 2007)", kit ref "CT3331873" (US ref CT3265309) comes up. This is the one I ordered. If I call it "iMac 2.4 GHz Intel Core 2 Duo (20-inch-667 MHz)" then kit ref "CT3331855" (US ref CT3265291) comes up. This is the one you suggest. The descriptions for both kits is identical so I'm not sure if there is any difference between the kits. I've asked Crucial this question and await their response. This is all very confusing and is driving me around the twist! I'll let you know when I know any more.

Expert:  Mike the Mac Medic replied 2 years ago.
Yes obviously if it is the correct RAM it should work unless you have a hardware failure. Try this again and maybe upgrade or reinstall the system:

Resetting the SMC & PRAM for Mac Pro, Intel-based iMac, Intel-based Mac mini, or Intel-based Xserve
1. Shut down the computer.
2. Unplug the computer's power cord.
3. Wait fifteen seconds.
4. Attach the computer's power cord.
5. Wait five seconds, then press the power button to turn on the computer.
6. Press and hold the Command-Option-P-R keys before the gray screen appears.
7. Hold the keys down until the computer restarts.
8. Release the keys.
Mike the Mac Medic and 3 other Mac Specialists are ready to help you
Customer: replied 2 years ago.

I've now upgraded the OS to Yosemite using 3GB RAM but been too busy to check what happens when I insert 4GB. If problem persists I will take computer to Apple for checking. Thank you for your help.