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
Processor: 2.4 GHz Intel Core 2 Duo
Memory: 2 GB 667 MHz DDR2 SDRAM (although 4 GB is actually installed)
Memory Slots:ECC: DisabledBANK 0/DIMM0:Size: 2 GB Type: DDR2 SDRAM Speed: 667 MHz Status: OK Manufacturer: 0x7F7F7F7F7F9B0000 Part Number: 0x4354324732533636374D2E4D3136464D0000 Serial Number: 0x00000000BANK 1/DIMM1:Size: Empty Type: Empty Speed: Empty Status: Empty Manufacturer: Empty Part Number: Empty Serial Number: Empty
NB: BANK 1/DIMM1 has the same type of memory module as BANK 0/DIMM0
What is the serial number of the iMac?
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
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:
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.
OK, tried that but no change. If both modules work in DIMM/0, does that not mean that the memory is OK?
Not necessarily did you blow out all the dust with an air can?
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?
The memory is from Crucial and is "4GB(2x2GB) DDR2-667 SODIMM MAC" & "CT2C2G2S667MCEU".
This is the one you should be using:
OK. I'll go back to Crucial and try that. Thank you.
OK let me know
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.
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.
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.