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Hi I installed 64GB of RAM into my iMac 4 x 16GB After the upgrade the system fails to boot. I can hear the hard drive, however the screen is off, with the old RAM the iMac works as expected. I have verified that the RAM is compatible and should work with my iMac. Any solution to get the iMac to work with the new RAM?
Ensure you have seated all RAM sticks properly in their slot, verified the keying matches and visually inspected the metal contacts between the RAM and the motherboard. There should no play in the installed RAM. This generally takes more force than is usually expected. Your system’s symptom is typically that of no RAM installed. Check back with more information as it becomes available to you.
This thread was helpful. I had to try every combination of configurations, i.e. ram chips in different slots, until it worked. I had 2 - 4GB OEM RAM chips installed in slot 1 and slot 3. I bought 2 - 8GB OWC RAM chips and it finally worked in this configuration: 4GB/8GB/8GB/4GB Machine is 27” iMac Retina
I had the same issue, mac not booting after RAM upgrade. I put the RAM sticks in the empty slots, but wouldn’t boot up. I took each of the new RAM out one by one and swapping them in the available slots, and figured that my second slot (from the bottom) is not working. I then decided to put the existing RAM in those sockets, to see if it does the same….nope, it booted. So then i added the new RAMs (in the sockets where the original sticks were) and it finally booted up and recognized all of them. Don’t know why it did this, but in the initial configuration it would boot with only one added stick in the top socket.
I read that it could take 30 seconds or more for the computer to initialize ram if some was added or the sticks rearranged. Did you wait at least 30 seconds after powering on with the new ram added?
I can only tell you what worked for me on my late 2009 iMac. After much frustration I pulled out the plastic tab all the way and at the same time inserted the new RAM with considerable force to make sure it was seated. Trust me you’ll know when it’s seated properly because it won’t move at all.
Of course, the RAM slot can be DOA / broken. If you have inserted a RAM stick in slot 4 and 1/2/3 it does not boot, and that stick works in slot 1/2/3 and you have inserted it properly it is perfectly possible. You can also try resetting the SMC by disconnecting power and waiting 15 seconds and then plug it back in, wait another 5 seconds and turn it on. And NVRAM / PRAM by turning off the mac and holding CMD+ALT/OPT+R+P and turn it on and hold until you see the progress bar. Please check Startup Disk, Display, and Date & Time settings as they may have been effected by the reset.
I had the same problem and tried every combo as well. I do believe the problem was it took longer to recognize the new ram and boot up. I just wasn’t giving it enough time. All is working great now with 64 GB ram installed
In my issue: I bought two sims Hyper with the same specs. except because they needs 1.2 volts. After a test a lot of combinations, iMac only work with the two OEM or with the two HYPER. It seems like OEM and HYPER are not compatibles.
I had the same exact problem. I had to insert 4-16-16-4 and it worked. Thanks very much!
Currently trying (& failing) at rebooting my iMac; I’ve tried these patterns thus far with no luck, 4 - 4 - 8 - 8, & 4 - 8 - 8 - 4 *going to try holding alt, cmnd , r + p while rebooting, and waiting patiently (it’s taking forever, but I can feel the machine response and my USB lights up, just nothing, but a sad blank screen. Thnx for the helpful thread !
Hi Alishaa, I had similar issues. I found that the key was to remove the old (original) RAM, put the new RAM into the old (original) RAM locations; and then put the old (original) RAM into the remaining slots.
I tried to add 32 GB of ram today to my new 2019 iMac and it wouldn’t boot (black screen). It was Crucial 2x16 GB memory that I added to my pre-installed 2x4GB ram. I tried every which way, every configuration and nothing worked. The computer only booted up properly when the original ram was in there (in any slots) without the new ram. Any suggestions??? I’m ready to return the memory!!
had this issue to, was gonna try original ram but realized one was just slightly loose. tried again, and kept ALSO resetting PRAM (CMD+ALT/OPT+R+P) with a usb keyboard (not wireless keyboard it came with) finally worked and don’t have to return the ram :)
I realized you can’t mix different brands of memory cards. Problem solved.
Hello, I have the same problem. I add 32gb ram to my iMac 2020 27 " After installing the ram, I waited about 2 minutes for the machine to finish booting. And currently my iMac is running with 40gb ram. I have read this message on the Apple’s support page: Note: Your iMac performs a memory initialization procedure when you first turn it on after upgrading memory or rearranging DIMMs. This process can take 30 seconds or more, and the display of your iMac remains dark until it’s finished. Make sure to let the memory initialization complete.
I had a similar problem with my 2020 27” iMac with Retina display. But I moved the original two memory sticks and inserted the new one. Mac would not boot. So I put the original sticks back in their original spots and slipped the new 32MB stick in an open slot and it booted up just fine.
I have two owc sticks of ram and after install the computer beeps three times. While testing them both in the empty slots, I accidentally removed one stick of old ram. I put it back but my Mac won’t recognize it. I don’t know why.
After countless hours of troubleshooting, trying different RAM in different slots, and speaking to AppleCare…. The problem was the controller… The iMac had to have the whole motherboard replaced (because Apple doesn’t repair that one piece) Thanks for your help everyone! Im surprised this thread had this much traction and I really appreciate all of the advice!
I have tried all sort of combinations moving from one slot to another in an IMAC 27 late 2014. I only managed to install 3 x 8gb Ram and after trying to install the last slot using the old 4gb RAM my Mac restarted with 3 beeps. So, I gave up and left my Mac with 24 gb instead of 32gb!
Hi, I just bought my new 27"inch 5K iMac and I got the same problem, after installing 8GBx2 2666 Mhz from OWC I got dark screen too. I am going to try another combination today because yesterday I only removed the new memory sticks and it worked again, so I will update on this as soon as I try another combinations.
I’ve solved this problem. first install the ram like this. SLOT 1 , 3 and 4. (leave slot 2 empty) if its boots up , the shut it down again and install on slot 2. this resolved the problem..
I had this problem when replacing 4 OEM 16 sticks with 4 OWC 32 sticks. The machine booted 1x and after that, black screen booth. tl; dr: I solved this by permuting all of the possible combinations of sticks after labelling them 1-4, based on that 1x boot order. I could get things to work with up to 3 sticks (1, 3, 4 and 2, 3, 4), but never (again) all 4. Slot 2 was the most problematic, because I could only get it to boot with certain chips in Slot 2. If I mixed in ANY combination of OEM chips, with Slot 2 always filled by a OEM stick… the machine booted just fine So, I did a SMC reset and PRAM reset. Didn’t work. Checked that the sticks were flush after re-installing the carrier every time. After it worked (fleetingly), I assigned each stick a #, 1-4, based on which slot they were in. So, I called OWC. We agreed that the best way to pursue this was to cycle sticks to see if there was any way to get it to boot. He suggested that I do a return and start over again, but my stubborn ass wouldn’t let it go. I then hunted around the slots. I started with which sticks would boot when installed in each of the slots. For me, my stick 1 worked in slot 1 and in no other slots. I repeated this for the other sticks, finding that stick 2 worked in slot 3 and four, but never 2. Stick 4 always worked in Slot 2. I used that as my anchor… Then I checked how the other sticks behaved. I found that I could boot on Stick 1 -> S1, Stick 3 -> S3, and inverse. Stick 2 -> S2, Stick 4 -> S4 never booted again, but Stick 4 -> S2, Stick 2 -> S4 always booted. Finally, I went with my Stick 1 / Stick 3 pattern, eventually getting a boot (after about 15 seconds) out of the 3, 4,1, 2 pattern. I have rebooted a bunch of times and completely cycled the power, including disconnecting the power at the wall. I have not done a PRAM reset as of yet. I’ll report back to OWC and here if things get messed up again.
