Model A1181: 1.83, 2, 2.1, 2.13, 2.16, 2.2, or 2.4 GHz Core 2 Duo processor

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What's causing backlight issue on startup after upgrading RAM?

A week or two ago I upgraded the RAM to 6GB as suggested here on ifix it with parts bought here.

Then since last Sunday the backlight will not work after waking from sleep mode or startup unless I go back and forth with the F1 and F2 keys for a couple minutes. After the backlight goes on it stays on just fine.

I tried reseting the PRAM and re-installing the RAM.

I'm hoping to fix this without buying any new hardware.

Update 3/19

I took out the 4 GB and put back in one of the original 1 GB RAM and the problem continued. Then I took out the 2 GB and replaced that one too with the other original 1 GB RAM. The computer backlight works just fine now. Is it possible that the 2GB RAM card that I bought has a problem?

Update 3/21

I check the firmware and it is up to date.

Then I tried each slot with each stick individually. All times the RAM was recognized but the problem continued except if the 4GB was on the left and the 2GB was on the right. So I tried them together in those positions and it seems to be okay. I'm going to observe this combination for a while to make sure it isn't a fluke.

Update 3/23

Still having issues. Only at startup except for when I plugged in my vampire of an external hard drive. My serial number is W89374679GU. I might try switching back to the original two RAM cards and see if the problem continues.

Thank you guys for your help!

Answered! View the answer I have this problem too

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Can you give us the last three digits of your serial number, so we can double check what your model is. It's possible your system is not one of the lucky ones that can be boosted to 6GB of RAM.


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2 Answers

Chosen Solution

After you do what Dan says, look at doing this:

Sometimes RAM slots fail. Try this: use the 2 GB stick only and first put it in slot 1 and boot. Next do this in slot 2. After each try check under the Apple with "about this Mac", more info > memory and see if it's reading all the RAM. Now do this with the 4 GB stick. See if you have have a bad slot. Sometimes a slot will read a smaller chip and not a larger one.

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Most Helpful Answer

Did you check the systems firmware level? I would start there. Follow this Apple TN EFI & SMC firmware updates for Intel-based Macs.

Exchanging memory modules shouldn't effect things this way directly. But it's possible the power needed for the newer module is just pulling a little more power effecting your systems stability.

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I had another thought during the night: Its possible the mapping of the video memory (which uses the higher address spaces of the installed RAM) is having problems. Are you sure the issue is the backlight Vs the display its self not able to display as the RAM space the GPU is using is not stable? If thats the case then you could have a bad module or slot as Mayer points out.


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