iMac 2019 - upgraded w 2 extra ram and the speed dropped to 2400 MHz?

[Kevbasscat]

Ugh. Got me on that one. I knew I should have looked it up.



Same here.

I recall that another reason for Hertz was that "cycles per second" was often just shortened to "cycles" or "megacycles" etc, losing the time element. Yeah, it was implied, but still.

No need to be right all the time, I'm rarely correct. I love learning and the word play is stimulation, not competition. I'll always learn more from you than you do from me. Funny how terminology changes with how we define and redefine. I've been reading up on single rank vs. dual rank and single side, vs dual sided. quite confusing until JEDEC defined it. I'll have something understandable tonight or tomorrow.

 

[Kevbasscat]

After spending a bit of time learning about single sided vs. double sided, and single rank vs. double rank, there was much confusion about these two different definitions and functions. They are however NOT the turd in the punchbowl of incompatibility, and lower clock speeds. My bad for the assumption, it's what I had learned from other MR posts. For clarity and because so many of us don't fully understand how DDR4 works very well, I'm attaching a pdf that explains these functions and why they aren't the culprit.

What I did learn however is there is on a great deal of DDR4 today an "XMP 2,0" profile by Intel. It modifies the bios to overclock for example 2400MT/s DDR4 to 2666MT/s, and thus manufacturers are advertising DDR4 at the higher "overlocked" speeds as normal DDR4. Since Apple does not support XMP 2.0, we get the DDR4's normal clock speeds, not the advertised speed. Very misleading.

Here is a quote from another Mr member concerning this. This is what is causing the majority of these 2019 iMac DDR4 mismatches. There should be some sort of truth in advertising law associated with this, but we all know what the chances of that are.

https://forums.macrumors.com/threads/2019-imac-ram-2400mhz.2176657/#post-27258169

Here is an Amazon DDR4 ad from Micron (Crucial's parent company), misleading someone on here with this kind of ad. Look down below the picture on the right for more info, you'll see they post this in a pretty inconspicuous spot, very easy to miss.

https://www.amazon.com/gp/product/B06XRBS4Y5

I am going to create a separate thread so that those who are still having this issue have something solid to work with and understand.

My advise? I ONLY buy ram that has been listed as "specifically for," my Mac. Either official Crucial, or some other OEM who manufactures their own ram and lists it as specifically for my model only.

P.S. @SaSaSushi, and others, you were correct about the original Apple ram being comparable with the correct dual rank third party ram. I stand corrected, thank you.

 

[juniorjnr1]

I'm having exactly the same issue as the OP - same RAM, same config.

Wondering if they found a solution, and also, to confirm would I be better off removing the 2X4GB, dropping to 32GB and having the RAM run at 2666?

 

[kschendel]

Having enough RAM is far more important than having it run a few percent faster. If 32GB is enough for what you are doing, you might see a very small speed boost by removing the 2x4. Otherwise, don't worry about it.