Problems with Installing 4GB RAM on mid 2007 iMac

Please double check the specifications of the RAM recommended for your machine. If you are not sure there are many ways to check. First is to look in your manual, it will always tell you what memory is recommended. If you purchase memory that doesn't exactly match it will not work. The next way is with the old (working) memory in your iMac by running System Profiler (Command Spacebar and type System Profiler) then click on memory on the left and look under Memory Slots. For example on my iMac it states

Type: DDR2 SDRAM
Speed: 667 MHz

However my recommendation is to locate your manual and it will say EXACTLY what you need.

It's really that simple.

Regards,

Roger

I'm having the same problem with two sticks of 2gb pc5300 ram that I picked

Sorry, earlier post got cut off. Anyway, iMac won't boot with 2 sticks of pc5300 2gb ram from PNY that I bought at microcenter today. Package says it's mac compatible. Same as everyone else- either stick works fine with the factory 1 gb stick. I worry that getting to 4gb is not possible, since it seems like it won't boot with two 2gb sticks. I think the ram it self may be micron, so that may be the issue.

Jonathan,

It either isn't the correct RAM for your iMac or it was not installed correctly. Please refer to your manual for the specifications and installation instructions. If you don't have your manual available you can find it here.

As long as the specifications are correct and it was installed correctly it should run fine. However it's possible one of the sticks is bad, you can trouble shoot that by installing just one of the sticks at a time and start the machine.

Regards,

Roger

No, I'm sure it was the correct ram (PC 5300) and I installed it correctly- I'm not a noob and I've done this before. Both sticks of 2 gb ram work fine if they are installed in either slot along with an additional 1 gb stick. Right now, I'm running 3 gb on my iMac and I have the other 2 gb stick installed in a netbook. Both work fine. They just won't work together in the iMac at the same time.

I know macs can be picky about timing, but this ram does have the MacOS logo on it, making me think that it's appropriate. Plus, when you buy from a retail store (microcenter), there's no way of knowing what the CAS timings are. Maybe the ram is just barely within apple specs, and when installed together, the latency is too long for the comp to boot. I don't know- but from the box, it IS the correct ram and it WAS installed correctly.

Honestly, between this problem and the fact that this model won't run a 64 bit kernel despite having a Core2Duo, I'm quite disappointed. If it was not for the investment in the massive 24 in. screen, I'd consider moving on.

It looks like the RAM you have isn't correct for some reason, I would return it to Micro Center. You can get RAM from OWC, in fact here is the link:

http://eshop.macsales.com/item/Other%20World%20Computing/53IM2DDR4GBK/

This should work without any problem.

BTW your iMac (assuming your signature is correct) will run a 64 bit kernel, I have the same machine and it runs fine. Below is the information on my machine and I'm running 64 bit right now.

Model Name: iMac
Model Identifier: iMac7,1
Processor Name: Intel Core 2 Duo
Processor Speed: 2.8 GHz
Number Of Processors: 1
Total Number Of Cores: 2
L2 Cache: 4 MB
Memory: 4 GB
Bus Speed: 800 MHz
Boot ROM Version: IM71.007A.B03
SMC Version (system): 1.21f4

Well, don't really want to take the ram back because I got such a good deal on it- they had the package mislabeled and sold it for $69. I don't mind splitting up the dimms, and I'm hoping that I could buy one more 2 gb dimm and it would work with the installed one. For now, 3 gb is ok, and the benchmarks I've run have shown very little performance decrease, and some show an increase, but I'm sure most of that is error.

As for the 64 bit kernel, how did you do that? As per this document...
http://support.apple.com/kb/HT3770

The mid 2007's do not support the 64 bit kernel.

Got it on the memory I suspected you were motivated by the price sometimes that just doesn't work out. 🙂

Here is the Apple Article that states which iMac's are 32 bit and which are 64 bit:

http://support.apple.com/kb/HT3696

It pretty clearly says the Core 2 Duo is a 64 bit processor. However the 24" late 2007 iMacs came with both a Core Duo (2.4 GHz) or the optional Core 2 Duo (2.8 GHz), the Core Duo is 32 bit the Core 2 Duo is 64 bit. Look closely at System Profiler to see which processor you have.

Now to get your iMac to boot in 64 bit all you need to do is hold down the 6 and 4 keys when it boots up.

If you want to know if your iMac has the 64 bit kernel run this command in Terminal:

ioreg -l -p IODeviceTree | grep firmware-abi

The result will say:

EFI64 is it's 64 bit or EFI32 if it's 32 bit.

That should do it.

Roger

I'm having this bad upgrade experience as well. My first 2x2GB RAM kit was Corsair "MacReady". Each module worked in either slot in combination with my existing !GB SODIMM, but computer would not start if both 2GB modules were installed together. Called Apple who suggested it was a minor incompatibility, to have MicroCenter replace the RAM. I replaced it with a Crucial 2x@GB kit, and had exactly the same scenario. I confirmed in the manual (pulled by serial number), as well as the System Profiler that I had the correct RAM. Has anyone found a fix for this, or does Apple have another issue they don't want to own up to? (Like the Superdrive firmware problem in my last MacBook Pro, for instance.)

There is nothing to for Apple to "own up to" the machines work as advertised. Have you done a SMC and PRAM reset? If not I would do that after installing the new RAM and if you still have problems return the RAM to Micro Center and purchase either:

http://www.crucial.com/

or

http://eshop.macsales.com/shop/apple/memory/iMac

paying a few extra dollars and getting the correct RAM Last you can bring your iMac into an Apple Store, pay a lot more and have them install the RAM they sell.

+I confirmed in the manual (pulled by serial number), as well as the System Profiler that I had the correct RAM.+

No, this has nothing to do with Apple. From whom did you get the Crucial kit? The incompatibility is a self-admitted Crucial problem. Have Crucial replace the RAM, they guarantee it all. However, you must tell them for exactly which Mac and that you need a different component build, according to Crucial customer service.

http://discussions.apple.com/thread.jspa?messageID=10341406&#10341406

Followup to my RAM upgrade saga. I did take the Crucial back and to MicroCenter and replace it with slightly more expensive "MacReady" RAM from Centon, who I had earlier misrepresented as Corsair. The first Centon RAM was marked as DDR2-667, the second as DDR2-800/667/533. Both are marked on the package and marketed as being "iMac Intel" compatible. Result? The symptom is exactly the same as with the first two sets of RAM, the iMac doesn't boot, no startup tones or anything but the quiet whir of a fan. Since the computer is under AppleCare I took it to the local Apple Store who "did not have 4GB test RAM" to prove the machine would work correctly with Apple RAM, nor did they stock the 4GB RAM for this 2-year old computer because it was "too old, and they only have so much space". And of course they will make no effort to support or troubleshoot the machine with aftermarket RAM.
For those who have posted replies to my first entry, I hope that you are speaking from your personal experience upgrading the mid-2007 iMac with 4GB RAM. If you are I would really like to know if it worked for you. If you are not speaking from personal experience specific to this machine and issue, I would ask that you withhold your comments so they are not unintentionally misleading. While I appreciate your support (that is why I posted my dilemma here), I'm trying to separate what "should" work from what "did" work for others.

I replaced my mid 2007 24" iMac with 2 x 2 GB RAM = 4 GB total. and am using it it to type this post. The Correct RAM for your iMac is:667 MHz, PC2-5300, DDR2 compliant NOT DDR2-800/667/533. This forum has had many many posts from people that have tried to use memory that is not 100% to the specification. Most have failed, a few have been successful. My recommendation is to go to

http://eshop.macsales.com/shop/apple/memory/iMac/IntelCore_2Duo

and order the correct RAM. This would be the:

http://eshop.macsales.com/item/Other%20World%20Computing/53IM2DDR4GBK/

In 2007 I purchased the same 4GB of third party RAM for both my iMac and my MacBook. I never buy RAM upgrade modules directly from Apple. I absolutely guarantee that 2007-dated Ram will operate your iMac as well as it does mine or my MacBook. I would probably be having the same problem as you if I were to be buying 2009-dated RAM today.

The fact is:
Most of the 2 x 2GB modules of today are not the same component build as were the 2 x 2GB modules manufactured two years ago. The cost to the consumer of 2009-dated RAM is dramatically lower. Components (the little black chips on the modules) are today being manufactured differently by the big industry leaders, as these RAM manufacturers have switched to increase efficiency and reduce their costs.

Your solution would be to purchase from old inventory (if this were practical) or to purchase from a seller who is able or willing to sell the older style product. I am sure there are some manufacturers who haven't yet upgraded their production lines - I just don't know for sure which they are. I regret that I'm unable to be of more assistance.

Thanks for the feedback. At this point I have not resolved the issue, but instead have chosen the path of least resistance - run 3GB RAM and expend my energy on more important things in life.