RAM Slots

themediadude

macrumors newbie
Original poster
Aug 11, 2017
16
1
Can I put my OWC (2) 16GB sticks in the factory RAM slots and move the factory RAM to the other slots? Have anyone done this, will I have any issues?
 

gian8989

macrumors 6502
Oct 23, 2015
273
77
Can I put my OWC (2) 16GB sticks in the factory RAM slots and move the factory RAM to the other slots? Have anyone done this, will I have any issues?
yes you can. I haven't done it but you won't have problems since owc ram should be same as mac (same cl like crucial).
 

czacha

macrumors member
Jul 9, 2017
76
24
But if you put RAM with different CL then you should remove original RAM so new one could work with full speed.
 

SaSaSushi

macrumors 601
Aug 8, 2007
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Takamatsu, Japan
But if you put RAM with different CL then you should remove original RAM so new one could work with full speed.
It depends. I am running 32GB of CL16 Crucial Ballistix together with 8GB of CL17 Apple stock RAM and it all runs happily at CL17, the lowest common denominator. I'm happier with the extra 8GB than the marginal and imperceptible (aside from benchmarks) increased performance of the CL16 Ballistix.

Eventually I'll add another 32GB of Ballistix.
 
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czacha

macrumors member
Jul 9, 2017
76
24
It depends. I am running 32GB of CL16 Crucial Ballistix together with 8GB of CL17 Apple stock RAM and it all runs happily at CL17, the lowest common denominator. I'm happier with the extra 8GB than the marginal and imperceptible (aside from benchmarks) increased performance of the CL16 Ballistix.

Eventually I'll add another 32GB of Ballistix.
I guess it all depends of work you do on computer. I'm a professional photographer. In Lightroom and Photoshop I've never reached 16GB of RAM on my older Mac.. so with 32GB I'm prepered for everything ;)
 

SaSaSushi

macrumors 601
Aug 8, 2007
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Takamatsu, Japan
I guess it all depends of work you do on computer. I'm a professional photographer. In Lightroom and Photoshop I've never reached 16GB of RAM on my older Mac.. so with 32GB I'm prepered for everything ;)
No, I think you may have misunderstood me. I have already added 32GB to the 8GB of stock RAM so I am currently at 40GB total.

I'm just saying that the speed loss involved in mixing RAM with different CAS latencies is so negligible that it won't make any noticeable difference in performance.

Eventually I will replace the 8GB of Apple RAM for another 32GB of Ballistix for 64GB total and get that little boost of performance from CL17 to CL16.

As a professional photographer I'm sure you will make full use of the extra RAM on your new machine. As for me, my work requires me to run virtual machines so I need the extra real estate as well.
 
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czacha

macrumors member
Jul 9, 2017
76
24
I get you mean, but I said that I don't need more than 32GB of RAM with Photoshop and Lightroom so there is no need for ME ;) to keep original 8GB of RAM when I put 32GB ;)
 

DeltaMac

macrumors G4
Jul 30, 2003
10,342
2,739
Delaware
Your system will use whatever RAM you want to have installed.
There's no downside to leaving other RAM installed, in addition to what you might have added.
 

themediadude

macrumors newbie
Original poster
Aug 11, 2017
16
1
Great, so the 32.0GB (2x 16GB) 2400MHz DDR4 SO-DIMM PC4-19200 SO-DIMM 260 Pin CL17 Memory Upgrade Kit will work just fine from OWC?
 

EugW

macrumors G3
Jun 18, 2017
8,446
5,801
And Crucial is less expensive as well.
Interesting. In the past OWC was cheaper than Crucial when I've looked. I didn't realize that now Crucial is actually cheaper. So basically no reason to go with OWC now, except if Crucial is out of stock.

I don't want to knock OWC too much as they reportedly provide good service and reasonable product, but one big difference here is Crucial is the actual manufacturer (or at least their parent company is) whereas OWC is just some store sourcing RAM from who knows where.
 
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snowtrooper1966

macrumors 6502
Oct 13, 2011
258
176
Clarksburg, WV
I completely removed the stock RAM when my iMac arrived last week, installed my 32GB (2x16) Crucial in primary slots 0&2, then stock 8GB(2x4) into secondary 1&3

May have been a bit overkill, but since my 1st iMac arrived a week earlier DOA/intermittent power on, I didn't want to take any chances of improperly seated sticks causing any sort of similar issue.
Made sense (unfounded by any actual research, LOL) to put the larger modules in the stock location....

IMG_4692.JPG
IMG_4693.JPG
 

JVNeumann

macrumors member
Mar 23, 2017
85
26
For me, I actually couldn't get the computer to boot until I moved the original 8GBs to the empty slots, and inserted the 32GB Crucial (16CL, I think) into the slots that were previously occupied. I tried more than half a dozen times over a couple of days, so it definitely wasn't just some freak occurrence. And yes, in some cases I left it 10-20 minutes to ensure it wasn't just taking extra time to detect the new RAM.

But with the slots swapped it detects the full 40GB now, so I'm not too fussed.
 

EugW

macrumors G3
Jun 18, 2017
8,446
5,801
For me, I actually couldn't get the computer to boot until I moved the original 8GBs to the empty slots, and inserted the 32GB Crucial (16CL, I think) into the slots that were previously occupied. I tried more than half a dozen times over a couple of days, so it definitely wasn't just some freak occurrence. And yes, in some cases I left it 10-20 minutes to ensure it wasn't just taking extra time to detect the new RAM.

But with the slots swapped it detects the full 40GB now, so I'm not too fussed.
That’s because you bought the wrong RAM.
 

JVNeumann

macrumors member
Mar 23, 2017
85
26
That’s because you bought the wrong RAM.
How's that? I followed a link that was recommended by several people in that big RAM thread, and checked the name as well to ensure the link wasn't being localized and changing the product slightly. Come to think of it, there might've been some mention of iMacs in the Amazon reviews too.

Plus it ended up working - surely if it was wrong it just wouldn't work at all...?

EDIT: I think I said it was Crucial in my previous post, but it was actually "Ballistix Sport LT DDR4 2400 MT/s (PC4-19200) SODIMM 260-Pin"

Plus the review I saw
 
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EugW

macrumors G3
Jun 18, 2017
8,446
5,801
How's that? I followed a link that was recommended by several people in that big RAM thread, and checked the name as well to ensure the link wasn't being localized and changing the product slightly. Come to think of it, there might've been some mention of iMacs in the Amazon reviews too.

Plus it ended up working - surely if it was wrong it just wouldn't work at all...?

EDIT: I think I said it was Crucial in my previous post, but it was actually "Ballistix Sport LT DDR4 2400 MT/s (PC4-19200) SODIMM 260-Pin"

Plus the review I saw
Yep. That is the wrong RAM.

Ballistix RAM is indeed a Crucial brand but it has the wrong RAM timings for use in conjunction with the stock RAM.

I wish people in that thread would stop recommending the wrong RAM but they continue to do so.
 
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kestasm

macrumors newbie
Jun 26, 2017
4
0
I get you mean, but I said that I don't need more than 32GB of RAM with Photoshop and Lightroom so there is no need for ME ;) to keep original 8GB of RAM when I put 32GB ;)
Does Lightroom work well? For me tragically.
 

JVNeumann

macrumors member
Mar 23, 2017
85
26
Yep. That is the wrong RAM.

Ballistix RAM is indeed a Crucial brand but it has the wrong RAM timings for use in conjunction with the stock RAM.

I wish people in that thread would stop recommending the wrong RAM but they continue to do so.
...Goddamnit. I swear I saw like 3 or 4 consecutive endorsements of it on that thread. So does that invalidate the 8GB of original RAM then? Is so, I had been considering eventually swapping them out with another 32 anyway, so maybe I can just fast-track that plan.
 

flyinmac

macrumors 68040
Sep 2, 2006
3,576
2,452
United States
Personally I would recommend Crucial RAM. They are a top tier RAM vender. OWC is not.
One thing to note, is that OWC doesn't manufacture memory. They buy memory and place an OWC sticker on it (not always covering the original manufacturer label).

So... often it is a high end brand. But, if you want to be assured of which brand you are buying, then you could order a specific brand module.

I have at times purchased OWC modules that were actually labeled by Crucial, but had an additional OWC label placed on them.

I have also gotten different brands with OWC labels as well.
 

SaSaSushi

macrumors 601
Aug 8, 2007
4,104
497
Takamatsu, Japan
Yep. That is the wrong RAM.

Ballistix RAM is indeed a Crucial brand but it has the wrong RAM timings for use in conjunction with the stock RAM.

I wish people in that thread would stop recommending the wrong RAM but they continue to do so.
Please disregard this misinformation because it is completely incorrect.

The Ballistix has a slightly faster CAS latency than the Apple stock RAM (CL16 as opposed to CL17) but it is 100% compatible with the 2017 iMac. The only effect of this is that all RAM runs at the very slightly slower CL17 of the Apple RAM when installed together. This is borne out by my benchmarks.

Note that on Apple's own RAM upgrade pages there is the following:

Use Small Outline Dual Inline Memory Modules (SO-DIMM) that meet all of these criteria:
  • PC4-2400 (19200)
  • Unbuffered
  • Nonparity
  • 260-pin
  • 2400MHz DDR4 SDRAM
The Crucial Ballistix is all of the above. I have been using it in my 2017 iMac for two months now in addition to the Apple stock RAM with flawless performance and several others in this forum are doing the same.

The distributor that sells the Ballistix for Crucial in Japan, CFD has posted to the Amazon Japan sale page for the Ballistix that they have tested it in the 2017 iMac and it works just fine.

...Goddamnit. I swear I saw like 3 or 4 consecutive endorsements of it on that thread. So does that invalidate the 8GB of original RAM then? Is so, I had been considering eventually swapping them out with another 32 anyway, so maybe I can just fast-track that plan.
The Ballistix is perfectly compatible with the 2017 iMac. I cannot say why it didn't work for you with the Apple stock RAM in DIMM0 but I CAN say with absolute certainty and personal experience that it is not because the Ballistix is incompatible or the wrong RAM.

Perhaps it wasn't seated properly? It works fine for me (and others in these forums) in both configurations.

I recommend trying the following: First, install only the Apple RAM in DIMM0 and boot the machine. Once that is working, shut down and then add the Ballistix in DIMM1, being sure to seat the DIMMs firmly and to fully wait out the black screen on first power up.
 
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EugW

macrumors G3
Jun 18, 2017
8,446
5,801
Please disregard this misinformation because it is completely incorrect.

The Ballistix has a slightly faster CAS latency than the Apple stock RAM (CL16 as opposed to CL17) but it is 100% compatible with the 2017 iMac. The only effect of this is that all RAM runs at the very slightly slower CL17 of the Apple RAM when installed together. This is borne out by my benchmarks.

Note that on Apple's own RAM upgrade pages there is the following:

Use Small Outline Dual Inline Memory Modules (SO-DIMM) that meet all of these criteria:
  • PC4-2400 (19200)
  • Unbuffered
  • Nonparity
  • 260-pin
  • 2400MHz DDR4 SDRAM
The Crucial Ballistix is all of the above. I have been using it in my 2017 iMac for two months now in addition to the Apple stock RAM with flawless performance and several others in this forum are doing the same.

The distributor that sells the Ballistix for Crucial in Japan, CFD has posted to the Amazon Japan sale page for the Ballistix that they have tested it in the 2017 iMac and it works just fine.



The Ballistix is perfectly compatible with the 2017 iMac. I cannot say why it didn't work for you with the Apple stock RAM in DIMM0 but I CAN say with absolute certainty and personal experience that it is not because the Ballistix is incompatible or the wrong RAM.

Perhaps it wasn't seated properly? It works fine for me (and others in these forums) in both configurations.

I recommend trying the following: First, install only the Apple RAM in DIMM0 and boot the machine. Once that is working, shut down and then add the Ballistix in DIMM1, being sure to seat the DIMMs firmly and to fully wait out the black screen on first power up.
Sorry, but this is one of the examples in that thread that I was talking about.

If you plan on using the stock RAM in conjunction with aftermarket RAM, Ballistix is indeed the wrong RAM. Buying the right RAM means getting the exact match with the exact same timings. It should not matter at all what RAM slot configuration you use, because it will still boot, if you have matched the timings correctly. If you buy one with the wrong timings, in certain machines, setting it up with the wrong DIMM slot configuration will mean the machine may not boot. It has nothing to do with DIMM seating.

However, if you plan on using it WITHOUT the stock RAM, then the Ballistix RAM is fine to use.

BTW, your posted Geekbench results are not necessarily representative, unless you ran them 5X in a row and got the same results, because people get that level of variation on the exact same machines with no changes in the hardware. Those results are within the margin of error for Geekbench. For example, I also got well over 5800 single-core on an i7 7700K iMac, with the stock RAM installed (along with matched Crucial RAM - total 24 GB). In fact, the score was 5821, which is actually faster than your Ballistix score. The multi-core was 20046.
 
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