16GB ordered, we'll see how it works on its own without the 8GB and then I will order another 16GB. The iMac arrived a day early !
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1.35 V & 1.5 V RAM for late 2013 iMac's
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16GB ordered, we'll see how it works on its own without the 8GB and then I will order another 16GB. The iMac arrived a day early !
Got the 16GB of G.Skill memory installed today. This gives me an approx 5% boost over 8GB of the Apple Memory. The momory shows up as 1867 in System Info.
http://browser.primatelabs.com/geekbench3/264429 [16GB G SKILL]
http://browser.primatelabs.com/geekbench3/259658 [8GB Apple RAM]
Geekbench just updated their suite for support of the 2013 iMac 16GB test run with new version.
According to the official JEDEC specs for DDR3L as well as Kingston's own website:
If you add 1.5V RAM to the stock Apple 1.35V RAM, as I have done, all of the modules will run at 1.5V and you should have zero issues.
That said, it would be nice to add DDR3L if you can for the power savings.
To further illustrate the compatibility of the stock Apple DD3L RAM with DDR3, here is a screenshot I took of TechTool Pro 7.
I ordered my Late 2013 iMac with 16GB (2x8GB) and I recently added these DDR3 1.5V modules to upgrade it to 32GB total.
The machine has been rock solid with the new RAM, no kernel panics and no system instability.
If there are 1.5V modules out there that are not compatible with the Haswell iMacs, it is not because of their voltage rating.
I ordered my Late 2013 iMac with 16GB (2x8GB) and I recently added these DDR3 1.5V modules to upgrade it to 32GB total.
The machine has been rock solid with the new RAM, no kernel panics and no system instability.
If there are 1.5V modules out there that are not compatible with the Haswell iMacs, it is not because of their voltage rating.
As mentioned, DDR3L 1.35V RAM is obviously fully supported, but so are standard DDR3 1.5V modules.
Good quality DDR3L is also more expensive, at least here in Japan. Aside from the voltage, the specs are identical. Again, DDR3L will run perfectly at 1.5V.
Personally, I'm not overly concerned with the minimal increase in power consumption on my desktop Mac anyway and I've had no heat issues to speak of.
Good quality DDR3L is also more expensive, at least here in Japan. Aside from the voltage, the specs are identical. Again, DDR3L will run perfectly at 1.5V.
Personally, I'm not overly concerned with the minimal increase in power consumption on my desktop Mac anyway and I've had no heat issues to speak of.
Using 1.5V on new iMac ( 4 modules together ) will cause Kernel panic under Mavericks and BSOD under Windows.
While I can't dispute that claim from personal experience, having not populated all 4 slots with 1.5v-only modules, I find it highly doubtful that the voltage was the cause of your problems. While half of my modules are DDR3L, they are all running at 1.5v. Haswell has no problems powering 1.5V RAM.
Furthermore, on Apple's own technical specifications page for the Late 2013 iMac, they make no mention of low voltage RAM at all. In fact, they specify:
8GB (two 4GB) of 1600MHz DDR3 memory; four user-accessible SO-DIMM slots
Configurable to 16GB or 32GB.
Contrast this with the specs page for the Late 2013 rMBP and you can see they do clearly know the difference and specify (for example):
8GB of 1600MHz DDR3L onboard memory
Configurable to 16GB.
Even on the Memory Specifications page for the iMac, it's all about DDR3.
My personal opinion is that Apple started shipping iMacs in 2012 with the 1.35v RAM in order to streamline orders from their suppliers with the notebook line, for which the lower powered DDR3L has a far greater meaning.
At any rate, if you are experiencing crashes with all 1.5v modules, I think you're just dealing with incompatible RAM. The fact that it's 1.5V is circumstantial and irrelevant.
It has been proven that the iMac Haswel series can't provide enough power to 4 DIMMs at 1.5V. Crucial was initially shipping 1.5V DDR3 RAM flagged as compatible with iMac before. They replaced it with 1.35V now due to complains from customers experiencing frequent random crash on with 32 GB installed.
There are dozens of threads and discussions here and on Apple Website related to Kernel panic with 32 GB or RAM. Crucial customers were most of the victims reporting this issue.
If you look at all vendors ( Crucial, Kingston, Samsung, OCZ etc.. ) All their iMac 2013 compatible Memory Modules are Low Voltage one.
You certainly can use 2 DIMMS at 1.5V but you will get a lot of headache with 4 operating slots.
Every RAM can work at 1.35V/1.5V and 1.65V if overclocked. It's not the voltage that matters, it's the stability.
That's why on some systems, when you overlock the RAMs by increasing the voltage, it might work for some time but also it might cause system instability.
Trust me, I've been there and loaded couple of Memory kits and observed different results. iMac Haswell can take 32 GB at 1866MHz with no issue whatsoever although Apple doesn't mention anything about it.
What Apple says isn't what the system can do or can't. I learned to never trust everything I read.
Also my 8GB x 4 are CL9 ( lower latency than the ones installed ). Apple says that the CAS latency should be 11 but then... it's Intel who decides not Apple. I'm more than happy with mine and system uptime is 28 days so far. Crossed fingers.
My 2 cents..
Can you provide a link to this proof by any chance?
Could that not be evidence that the problem was Crucial and not the voltage?
This is true. I don't dispute it. It's not proof that the iMac doesn't support DDR3 RAM, however.
I'm not trying to call you a liar or discredit your opinion. I'm just asking if it wouldn't be in Apple's best interest to specify DDR3L RAM in their memory specs for the iMac if that was, in fact, required.
It would be no skin off their teeth to do so, and if it was a factor for increased stability, I would think it to be highly beneficial for them.
In the data sheets spec for Haswell from Intel it says "supports low power RAM", but that hardly means it doesn't support standard DDR3 at 1.5v.
Almost all of the issues I've seen on the web with Haswell and RAM voltage is OCing to 1.65v, as you mentioned.
I appreciate your opinions.
Ok where to start. Pardon my laziness but I'm making an effort at 3 AM digging all the threads.
https://discussions.apple.com/thread/5519900?tstart=0
https://forums.macrumors.com/threads/1678026/
http://forum.crucial.com/t5/Apple-M...restarts-itself-once-a-day/td-p/136875/page/7
I have omitted the macrumors threads because you can find it yourself.
Long story short. All the headache with Crucial customers was because the compatible RAM listed was SKU CT2C8G3S160BMCEU.M16FDD ( 1.35v/1.5V )
They replaced it with CT102464BF160B
8GB DDR3L-1600 SODIMM ( DDR3L 1.35V )
To be honest with you, the 1.5V modules are cheaper than the low voltage ones. We all know Apple; if anything, they would have shipped the late 2013 with 1.5 modules. In our case, the new iMac is shipped with DDRL3 ones.
I hope I convinced you.
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Thanks for your efforts.
I am familiar with the links you provided from here and the Apple Discussion Forums. I had not seen the Crucial Forums thread though.
Curiously, all of the threads you provided were from users of Crucial RAM. In the Apple Discussion Forums thread, the very last post of a few days ago was someone getting kernel panics with a set of low power Crucial 1.35V modules that they got via an RMA! That, in itself, should suggest that the problem may be other than the voltage.
As I said, please refer to the very last post (as of this writing) by Ginooken who is still getting kernel panics with the 1.35v replacement and in the post prior to that one someone else mentions they were told by Crucial that the problem was narrowed down to a PC board (manufacturing) problem with the modules, not voltage.
Someone has put two and two together and gotten other than four with these 1.5v DDR3 being incompatible claims.
An acquaintance here in Japan works with Micron Japan at one of their DRAM fabs in Hiroshima. They are making RAM for the iPad and we've discussed this kind of thing. At the amounts Apple is being supplied, it may not be the case that DDR3 is less expensive.
Likewise. Otherwise, I'm afraid we'll just have to agree to disagree.
1.5V is the JEDEC standard voltage for DDR3, which Intel (and Apple) says Haswell-based computers like the iMac support, no matter how many modules are in use.
From what i've researched iMac's can handle both 1.35 V & 1.5 V RAM.
I'd like to know if either voltages is a better option for the Haswell iMac's.
Could adding 1.5 V potentially harm the computer or is 1.35 V more of a power saving measure?
My hunch is the 1.5 V in an iMac would be fine and 1.35 V would optimise a MBP.
I had ordered Kingston HyperX Plug & Play 1.5V http://www.amazon.co.uk/gp/product/B008H7IGGI/ref=oh_details_o01_s00_i00?ie=UTF8&psc=1 due to it's low latency but know of a more expensive 1.35 V version. I'm wondering whether it's worth getting a lower voltage module set to optimise my computers lifespan.
Any advice or opinion would be really helpful.
I'll just get straight to the point
I upgraded my late 2013 with Corsair Value Select Low Voltage 4GB * 2 (in addition to the Apple original) and it works like charm.
Go for the lower voltage.
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I just want to share my experience because I have read a lot and I still don't know what to think.
I installed CORSAIR Vengeance, CMSX16GX3M2A1600C10, 4x 8GB, DDR3-SODIMM, PC3-12800 (1600MHz), CL10, 1,5V on my Late 2013 Imac 27.
For more information you can read my other post:
https://forums.macrumors.com/posts/18668885/
I installed CORSAIR Vengeance, CMSX16GX3M2A1600C10, 4x 8GB, DDR3-SODIMM, PC3-12800 (1600MHz), CL10, 1,5V on my Late 2013 Imac 27.
For more information you can read my other post:
https://forums.macrumors.com/posts/18668885/
Well, I want to make an update on this matter and a mea culpa.
After everything I wrote previously in this thread and all the testing I did with the 1.5V RAM added to the Apple stock 1.35v RAM, I started to get random system lockups. They seemed like kernel panics, only I didn't get the on screen message. It just went grey and froze completely. It usually happened while using a Flash-based web conferencing tool for my job.
I removed the new 1.5v RAM and returned it. I have since ordered 16GB of DDR3L and it will arrive today so I'm hoping for better results.
However, I think the real problem may have been my attempting to run the Apple stock 1.35v RAM together with the 1.5v and not a total incompatibility with the higher voltage modules. I didn't have the time to remove the Apple stock RAM to try the 1.5v alone to test it but I suspect it would have been fine. I specifically bought this iMac with 16GB (2x8GB) so that I would only have to add 2 modules rather than replace any.
I will report back after I've added the 1.35v modules.
I would say that those who are running 1.5v only and have no issues have nothing to worry about but I'd strongly advise against mixing voltages. If you buy your iMac with the intentions of adding to the stock RAM, stick with DDR3L.
After everything I wrote previously in this thread and all the testing I did with the 1.5V RAM added to the Apple stock 1.35v RAM, I started to get random system lockups. They seemed like kernel panics, only I didn't get the on screen message. It just went grey and froze completely. It usually happened while using a Flash-based web conferencing tool for my job.
I removed the new 1.5v RAM and returned it. I have since ordered 16GB of DDR3L and it will arrive today so I'm hoping for better results.
However, I think the real problem may have been my attempting to run the Apple stock 1.35v RAM together with the 1.5v and not a total incompatibility with the higher voltage modules. I didn't have the time to remove the Apple stock RAM to try the 1.5v alone to test it but I suspect it would have been fine. I specifically bought this iMac with 16GB (2x8GB) so that I would only have to add 2 modules rather than replace any.
I will report back after I've added the 1.35v modules.
I would say that those who are running 1.5v only and have no issues have nothing to worry about but I'd strongly advise against mixing voltages. If you buy your iMac with the intentions of adding to the stock RAM, stick with DDR3L.
You should have listened to me
Mixing RAMs of different voltage will run them at the highest voltage.
Haswell iMac will suffer random kernel panic and crash if 4 DIMMs are running @ 1.5V
I even tried the 32GB 1866MHZ 1.35V CL10 RAMs and system is rock solid since few days.
As said earlier, it looks like the PS can't provide enough juice to all DIMMs at 1.5V.
You should have listened to me
Indeed, I should have.
This I did know, but I was under the mistaken impression that DDR3L also supported 1.5v.
I do know that mobile Haswell-based CPUs do not support 1.5v memory but isn't the i7 in the iMac (i7-4771 in my case) a desktop processor?
This site says:
But I think it is mistaken.
I am using DDR3L Crucial CT2K8G3S160BM 1.35V/1.5V Mac
http://www.amazon.com/Crucial-PC3-1...T2K8G3S160BM/dp/B008LTBJFW/ref=cm_rdp_product
No kernel crashes yet and the system has been running hard . The reviews looked solid for the haswell iMacs so I went with this for my Haswell and maxed the ram out totaling 32GB I have 2 8GB Apple ram sticks and 2 Crucial Ram Sticks.
http://www.amazon.com/Crucial-PC3-1...T2K8G3S160BM/dp/B008LTBJFW/ref=cm_rdp_product
No kernel crashes yet and the system has been running hard . The reviews looked solid for the haswell iMacs so I went with this for my Haswell and maxed the ram out totaling 32GB I have 2 8GB Apple ram sticks and 2 Crucial Ram Sticks.
As an Amazon Associate, MacRumors earns a commission from qualifying purchases made through links in this post.
Well, I just added my 16GB of new DDR3L and everything seems fine but of course the true test will be in extended usage and in particular if I am able to use my Flash-based web conferencing app without system lockups.
I will report back with my results after a few days of use. Fingers crossed.
I bought this Team Group RAM:
I would have bought the Crucial DDR3L on Amazon US for $139.99 that many people in here praise but it isn't for sale at Amazon Japan.
For others in Japan, this was about the same price at current exchange than the Crucial without the international shipping and customs charges. PC-Ones has a no-questions-asked refund policy for any incompatibility issues within 2 weeks of purchase. They also have excellent service and usually close to the lowest RAM prices in the country at any given time.
I will report back with my results after a few days of use.
Fingers crossed. I bought this Team Group RAM:
I would have bought the Crucial DDR3L on Amazon US for $139.99 that many people in here praise but it isn't for sale at Amazon Japan.
For others in Japan, this was about the same price at current exchange than the Crucial without the international shipping and customs charges. PC-Ones has a no-questions-asked refund policy for any incompatibility issues within 2 weeks of purchase. They also have excellent service and usually close to the lowest RAM prices in the country at any given time.
As previously said I installed 4 Corsair Vengeance DIMMs at 1,5v and no problems for the moment, if something happen I will come back there to share feedback.
Can you check the voltage running across the module ?
1.35V/1.5V is different from 1.5V/1.65V
I don't beiieve that for 1 nanosecond.
First, there are countless people running 4 x Corsair 1600 CL10 1.5v in 2012 imacs and some in 2013 without problems. The 2012 and 2013 share the same power supply and the Haswell chips use give or take the same amount of power.
Second, the incremental power consumption of running at 1.5 instead of 1.35 volts is negligable. Around 3w total across the 4 sticks, and WAY less than the extra power used for example by overclocking the video card, which many people have tried and which works without issue. (Incidentally, that's 3w under full load. A fraction of that on idle - perhaps 0.1w).
Third, Apple - normally a very conservative bunch - state that 1.5v ram is fine in Haswell iMacs.
It is FAR more likely (strike that, it is an unavoidable conclusion) that people having issues with 4 x 1.5v sticks are down to compatibility of the specific brand and type of sticks themselves, rather than the voltage per se.
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