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New iMac 5K RAM upgradable?
- Thread starter netdudeuk
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A quick visit to the official iMac 5K specs page says that both the low-end and the high-end iMac models (like all 27" iMacs) have user accessible RAM slots, so yes, the RAM is upgradeable.
http://www.apple.com/imac-with-retina/specs/
It needs to be 1600Mhz, unbuffered, nonparity, 204-pin. It's not mentioned, but it should also be low-voltage (1.35V or supporting both 1.35V and 1.5V)
You can easily order this from a lot of RAM manufacturers.
You can combine it with the RAM already installed on your Mac or replace it completely for 16, 24 or 32Gb RAM.
https://support.apple.com/en-us/HT1423
Yes it is.
If you buy the stock 8GB, to get 16GB you can fill the other two free slots in the iMac with 2x sticks of 4GB 1600MHz 204-pin DDR3 memory.
UK: http://uk.crucial.com/gbr/en/imac-(retina-5k,-27-inch,-late-2014)/CT6313742
US: http://www.crucial.com/usa/en/imac-(retina-5k,-27-inch,-late-2014)/CT6313726
Edit: Ah, aevan beat me
If you buy the stock 8GB, to get 16GB you can fill the other two free slots in the iMac with 2x sticks of 4GB 1600MHz 204-pin DDR3 memory.
UK: http://uk.crucial.com/gbr/en/imac-(retina-5k,-27-inch,-late-2014)/CT6313742
US: http://www.crucial.com/usa/en/imac-(retina-5k,-27-inch,-late-2014)/CT6313726
Edit: Ah, aevan beat me
Note it has to be SO-DIMMs, DDR3, PC12800 (= 1600 MHz x 2 x 4 bytes per clock), CL11.
You could try shorter CAS latency (e.g. CL9) and faster clocks (e.g. 1866 MHz), but no guarantees.
Besides Crucial, Corsair is also selling "Mac qualified RAM".
I looked up the one you purchased at it says its "CL9". I see the one for $129 which is "CL11". But the post from "loekf", says it should be CL11, but how's it working for you?
this is the kit you normally find on the Crucial website:
http://eu.crucial.com/eur/en/imac-(retina-5k,-27-inch,-late-2014)/CT6313719
I have two of these in my 5k iMac.
Looks like you have this one:
http://eu.crucial.com/eur/en/ct2c8g3s1339mceu#reviewDetails
which is CL9.
I think Apple's official specs are CL11. CL9 *could* give you a 1-2% performance gain for some tasks, but no guarantees. The higher the clock speeds for memory these days, the less relevant CAS latency is.
You also have to careful if you add faster (CL10, CL9) RAM to the two already placed modules by Apple, which are CL11. Your iMac might decide to downgrade your RAM (e.g. to 1333 MHz).
I bought the one from Amazon that is the CL11 version after using the Crucial website to determine which memory was compatible. So far it has been working great, ran a few memory tests and it passed all. No crashes or waking up from sleep issues I've read about as well. I almost bought the CL9 from Microcenter before, because I noticed it was priced lower, but now glad I did not.
I have two CT6313719 kits (so 4 x 8 GB) in my 5k iMac. Works great. I can't find the number you mentioned on Crucial's website, but on Amazon.com I can. This kit can be found when you use the search tool on Crucial's website. The specs for this other kit on Amazon.com looks similar (1.35 V PC12800 1600 MHz SO-DIMM CL11).
You have to take into account that Intel CPUs (and AMD's as well) prefers to access two memory slots in parallel (interleaving). Suppose if you have 4 slots, let's say A, B, C and D. If you put a 2 GB in A, a 4 GB in B and 8 GB in C.. the CPU will access the banks indivually and you at least will get a performance hit.
It's preferred to have the same size, manufacturer in two slots next to each other, so e.g:
A - 4 GB (Apple puts it here by default)
B - 4 GB (Apple puts it here by default)
C - 8 GB (brand XX)
D - 8 GB (brand XX)
You also will get a performance hit, of 5-10%, because memory is not accessed via interleaving (also called dual-channel). Not sure how the memory controller works, but maybe the two upper slots (where Apple puts the two 4 GB modules by default) are accessed interleaved and the single 8 GB module is accessed in a single-channel way.
You will get a hit depending on where the memory is mapped in the address space.
Does your sleep function work. These chips from amazon cause issues whereby my unit sleeps and never wakes up.
I used 2 Sets of KingstonHyperX Impact HX318LS10IBK2/16 ram 16GB 1866MHz DDR3L CL10 SODIMM (Kit of 2) 1,35V, which gives me 32 Gig RAM. I works fine without any problems and is noticeable faster in Geekbench Memory test than the 1600MHz - CL11 DIMMs but not more expensive.
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Actually never use sleep mode. I think in screen lock mode with no processes active and the screen disabled, the CPU stays active.
Same here. It's been flying along without a hitch since day one.
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More expensive here. Trying OWC first.
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Lets be clear, the reports of wake issues are from people who bought CL11. You should not really use memory not designed for your device.
For me, I also don't want added memory to cause any hardware issue. I was at the Crucial site and there are many threads about this wake problem. Each time, Crucial acts like its news to them wiling, of course to exchange, but not willing to figure out whats going on. Posts back to the beginning of the year.
One poster indicated that the problem may be, that Apple memory chips (Samsung I believe) don't behave well with other chips.
For me, I also don't want added memory to cause any hardware issue. I was at the Crucial site and there are many threads about this wake problem. Each time, Crucial acts like its news to them wiling, of course to exchange, but not willing to figure out whats going on. Posts back to the beginning of the year.
One poster indicated that the problem may be, that Apple memory chips (Samsung I believe) don't behave well with other chips.