Mixing RAM in new 27inch 5k?

Vertigoo

macrumors newbie
Original poster
May 2, 2015
9
2
Hi,
today I bought the new Imac 5K and I love it!

It came with the 8 GB 1867-MHz DDR3 RAM.
In an official Apple retail store (Belgium) I asked them to add another 16GB.

They did add the 16GB, but they put in 1600-MHz DDR3 RAM instead of the 1867-Mhz RAM already installed.
They said it wouldn't make any difference in speed and also that it would not give any conflicts. They also said that at the moment they couldn't get the 1867 Mhz.

When I go to check 'about this Mac', it says that I have 24 GB of 1600 Mhz DDR3 RAM... (doesn't mention the 1867 Mhz RAM).

The only issue I have is that when I start the computer, after about a third of the process bar in the log in screen, the machine blinks, the log in screen disappears to come back a second later and then the process bar continues and I can log in fine. I must say that I used a terminal command not to hear the start up sound.

Will this difference in clocktime (MHz) make a difference in speed?
Will I get issues with my computer due to this?

I contacted Apple support and they said that it wouldn't make a difference.

Can anyone please give some advice?
 

redheeler

macrumors 604
Oct 17, 2014
7,631
7,364
The only issue I have is that when I start the computer, after about a third of the process bar in the log in screen, the machine blinks, the log in screen disappears to come back a second later and then the process bar continues and I can log in fine.
My late 2014 Retina iMac does this as well, nothing to be worried about.

------​
Will this difference in clocktime (MHz) make a difference in speed?
Will I get issues with my computer due to this?
All the RAM will run at 1600 MHz (including the 1867 MHz). You get a slight performance hit, but nothing hugely noticeable.
 

MacUser2525

macrumors 68000
Mar 17, 2007
1,974
304
Canada
When different speed ram is used together then the faster ram falls back to the lower speed rams running speed. Overall the speed of the machine will probably be a percent or two slower on benchmarks, real world day to day running no difference at all most likely unless you are doing a high memory load processing all the time. The machine blink you see on startup will be the graphics being initialized nothing to worry about.
 

xgman

macrumors 601
Aug 6, 2007
4,870
669
generally speaking it is a safer bet to use all the same ram. People have had issues here and there mixing. It should be fine, but if you start having any issues, check that first.
 

im2slick4u

macrumors newbie
Sep 22, 2015
29
1
Michigan
Don't mix two different frequencies of RAM. It can cause extreme issues in the prevention of errors in the code on your Mac. You could potentially crash your Mac and loose thousands of dollars or loose all of your apps and data on the computer. Only buy the same kind of RAM for the entire Mac. I would recommended ECC memory which stands for error correcting code which can automatically fix bugs in bad programs for you which actually improves the stability of the Mac.
 
Last edited:

CelestialToys

macrumors 6502
Aug 4, 2013
359
168
up above the streets and houses
Don't mix two different frequencies of RAM. It can cause extreme issues in the prevention of errors in the code on your Mac. You could potentially crash your Mac and loose thousands of dollars or loose all of your apps and data on the computer. Only buy the same kind of RAM for the entire Mac. I would recommended ECC memory which stands for extreme code correctness which can automatically fix bugs in bad programs for you which actually improves the stability of the Mac.
You probably shouldn't comment when you don't know what you're talking about.
 

im2slick4u

macrumors newbie
Sep 22, 2015
29
1
Michigan
You probably shouldn't comment when you don't know what you're talking about.
I actually took a computer operations in business and microsoft office class in high school last year so I am very educated on these types of machines. I also build custom pcs all by myself.
 

im2slick4u

macrumors newbie
Sep 22, 2015
29
1
Michigan
You may want to go back to school then. Almost everything in your comment is wrong.
Like what? Since you can't point out a single thing wrong with my statement you clearly don't know what you are talking about and YOU are the one who needs to go back to school. I help people build pcs all the time and i can code computers so I really do no my stuff. Don't go around calling people out on things you know nothing about.
 

CelestialToys

macrumors 6502
Aug 4, 2013
359
168
up above the streets and houses
Like what? Since you can't point out a single thing wrong with my statement you clearly don't know what you are talking about and YOU are the one who needs to go back to school. I help people build pcs all the time and i can code computers so I really do no my stuff. Don't go around calling people out on things you know nothing about.
Ok here we go then hot shot. ECC stands for Error correcting code, not extreme code correctness, and iMacs are not compatible with it anyway. The other stuff about not mixing frequencies of RAM is also not true. I await your apology, and in the meantime please stop spreading misinformation.
 
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Buerkletucson

macrumors 6502
Sep 12, 2015
477
265
Performance hit or not I believe the OP got ripped off.........
If he paid the going Apple rate for RAM (insanely priced) and they put in 1600 Mhz instead of 1867 Mhz I'd be pissed.

Why take any slight performance hit & not have matching RAM when you pay Apple a premium?
I'd demand the correct matching RAM or my money back.
 
Last edited:
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Vertigoo

macrumors newbie
Original poster
May 2, 2015
9
2
I am really getting confused now...
I'm not going to take any risk.
I removed the 16gb and will go back to the apple retail store tomorrow.
I will ask my money back and wait until the new RAM is available in Europe.
 
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CelestialToys

macrumors 6502
Aug 4, 2013
359
168
up above the streets and houses
Performance hit or not I believe the OP got ripped off.........
If he paid the going Apple rate for RAM (insanely priced) and they put in 1600 Mhz instead of 1867 Mhz I'd be pissed.

Why take any slight performance hit when you pay Apple a premium?
I'd demand the correct matching RAM or my money back.
Yup I totally agree with this. Personally I would take it back get a refund and then buy RAM from Crucial once it's available.
 

dborod

macrumors regular
Jul 22, 2002
127
53
I am really getting confused now...
I'm not going to take any risk.
I removed the 16gb and will go back to the apple retail store tomorrow.
I will ask my money back and wait until the new RAM is available in Europe.
I don't think there's any danger to the hardware or software in having slower RAM mixed mixed with faster RAM. All of the RAM will be accessed at the speed of the slowest RAM, so your computer will be slightly slower than it otherwise might be.

That said, you should get Apple to provide you with the fastest RAM that is compatible with the iMac.

Oh, and iMac's can't make use of ECC RAM.
 

im2slick4u

macrumors newbie
Sep 22, 2015
29
1
Michigan
Ok here we go then hot shot. ECC stands for Error correcting code, not extreme code correctness, and iMacs are not compatible with it anyway. The other stuff about not mixing frequencies of RAM is also not true. I await your apology, and in the meantime please stop spreading misinformation.
Lol learn to use Google and maybe you'll have some correct information instead of making up lies. This argument is over.
 

MacUser2525

macrumors 68000
Mar 17, 2007
1,974
304
Canada

CelestialToys

macrumors 6502
Aug 4, 2013
359
168
up above the streets and houses
Lol learn to use Google and maybe you'll have some correct information instead of making up lies. This argument is over.
Jeez. There was no argument. You were wrong. You still are wrong and you'll always be wrong.

I suggest that before you tell others to use Google that you at least take five minutes to use it yourself, then you wouldn't make yourself look silly.
 

im2slick4u

macrumors newbie
Sep 22, 2015
29
1
Michigan
Jeez. There was no argument. You were wrong. You still are wrong and you'll always be wrong.

I suggest that before you tell others to use Google that you at least take five minutes to use it yourself, then you wouldn't make yourself look silly.
No I'm pretty sure I'm right
 

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