Why won’t this ram work?

[h4lp m3]

I bought this Samsung RAM Upgrade, and it won’t work in my 2017 5K iMac, no matter what configuration I arranged them in.

The black ones came with the computer, and they work fine. The green ones do NOT work, even by themselves

 

[h4lp m3]

With the Samsung RAM installed, you can hear the fans and hard drive spin up, but there is no chime, no display, and no annoying 3 beeps like you usually get when there is bad or incompatible Ram

 

[Fishrrman]

I think the answer to your problem is going to be:
Try a DIFFERENT pair of RAM DIMMs.

 

[imrazor]

It looks like the green Samsung module is this one, based on the part number on the sticker:

Sam Original 8GB (1x8GB) DDR4 3200Mhz PC4-25600 SODIMM 1Rx8 CL22 1.2v RAM Memory Laptop Notebook Module Upgrade M471A1K43EB1-CWE Adamanta

Accelerate your programs and increase your system memory to 8GB , 16GB , 32GB , 64GB , or even 128GB with supported computer systems installing Adamanta Memory. Want to make sure this module works for your device? We offer free technical support from our own certified technicians. Memory modules ...

www.amazon.com

As noted in the Amazon listing, this is a 3200MHz RAM module, while the black module appears to be this:

16GB (1x16GB) Micron MTA16ATF2G64HZ-2G3B1 DDR4 2400 260-Pin Sodimm Laptop Memory

16GB (1x16GB) Micron MTA16ATF2G64HZ-2G3B1 DDR4 2400MHz PC4-19200 260-Pin SODIMM Laptop Memory

www.amazon.com

...which appears to be a 2400MHz RAM module. It seems likely that the green modules are too fast for your iMac.

 

[DeltaMac]

Or, try using ONLY the Samsung memory. Boot up to a NVRAM reset, by holding Option-Command-P and R.
You absolutely should get a boot chime during a boot while holding those 4 keys. If you get a boot chime, continue to hold the same 4 keys, until you hear the boot chime 2 more times, then release the keys and let your Mac boot normally. Does it boot successfully this time? If yes, do a normal shut down, and add the other ram. Boot with the same NVRAM reset, again holding the keys until you get the boot chime 2 more times. Should be good now. -- or, not. If your iMac still won't boot with that Samsung RAM, then return, and try a different brand.

 

[h4lp m3]

Or, try using ONLY the Samsung memory. Boot up to a NVRAM reset, by holding Option-Command-P and R.
You absolutely should get a boot chime during a boot while holding those 4 keys. If you get a boot chime, continue to hold the same 4 keys, until you hear the boot chime 2 more times, then release the keys and let your Mac boot normally. Does it boot successfully this time? If yes, do a normal shut down, and add the other ram. Boot with the same NVRAM reset, again holding the keys until you get the boot chime 2 more times. Should be good now. -- or, not. If your iMac still won't boot with that Samsung RAM, then return, and try a different brand.

I tried all of that 😰

 

[h4lp m3]

It looks like the green Samsung module is this one, based on the part number on the sticker:

Sam Original 8GB (1x8GB) DDR4 3200Mhz PC4-25600 SODIMM 1Rx8 CL22 1.2v RAM Memory Laptop Notebook Module Upgrade M471A1K43EB1-CWE Adamanta

Accelerate your programs and increase your system memory to 8GB , 16GB , 32GB , 64GB , or even 128GB with supported computer systems installing Adamanta Memory. Want to make sure this module works for your device? We offer free technical support from our own certified technicians. Memory modules ...

www.amazon.com

As noted in the Amazon listing, this is a 3200MHz RAM module, while the black module appears to be this:

16GB (1x16GB) Micron MTA16ATF2G64HZ-2G3B1 DDR4 2400 260-Pin Sodimm Laptop Memory

16GB (1x16GB) Micron MTA16ATF2G64HZ-2G3B1 DDR4 2400MHz PC4-19200 260-Pin SODIMM Laptop Memory

www.amazon.com

...which appears to be a 2400MHz RAM module. It seems likely that the green modules are too fast for your iMac.

Well, I’m just going to send them back. It appears that all PC4-2400T is not created equal

 

[MacInTO]

Well, I’m just going to send them back. It appears that all PC4-2400T is not created equal

It should theoretically work but for whatever reason maybe it cannot clock down to 2400 MHz. If it can clock down then it should work in a 2019 iMac at 2667MHz and your 2017 iMac at 2400MHz. Maybe it is bad quality RAM or corners were cut in manufacturing to make it incompatible? I have some bargain basement 2667MHz RAM in my 2017 iMac and there is also two sticks of 2400MHz Micron RAM in there and it works fine.

I find RAM fickle in Macs. You can buy 'mac' specific RAM but you pay the Apple tax. I go for the cheapest RAM that I think will work. Most of the time it does. Unfortunately in your case it did not.

Edit, I found this 3200MHz ram and it states it can only clock down to 2666MHz,

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www.amazon.com

From the description, "3200MHz Memory RAM can downclock to 2933MHz or 2666MHz if system specification only supports 2933MHz or 2666MHz"