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Memory upgrade troubleshooting in 2020 27-inch iMacs
- Thread starter KrazyKanuck
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You are not in dual channel. There is no way to really check it, but you are not for sure.
Only benchmarks and your level of satisfaction towards them will tell you.
May be not right based on this:
Memory upgrade compatibility list for iMac 2019-2020
Memory upgrade compatibility list for iMac 2019-2020
Try this again: adding the Novabench RAM speeds, as you requested (these are the maximums of 3 tests on each arrangement): slot 1 16GB crucial slot 2 16GB timetec slot 3 16GB crucial slot 4 16GB timetec gives 2133 MHz, Geekbench 8240, Novabench RAM speed 25660 MB/s :( slot 1 16GB crucial slot...
r.tapatalk.com
Since the stick sizes are the same, he should be fine for dual channel. It's when you mix different RAM sizes that would be an issue.
Yep.
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What about memory transfert speed in Novabench
This matches my finding, based on trying numerous different arrangements and benchmarks. See my posts in the "Memory Upgrade Compatibility Thread." Which I will repeat here for your convenience:
This is what I deduce from my experiments:
In order to get full RAM speed and performance using 4 sticks of RAM in the 2020 27" iMac, apparently need to satisfy all of the following conditions:
1. All sticks must be the same size (GB) and rank
2. Sticks in Slots 1 and 2 must be identical (including brand and part number)
3. Sticks in Slots 3 and 4 must be identical
Of course, the most straightforward and sure way to ensure all 3 conditions are met, is to have all 4 sticks identical.
However, it is apparently possible to mix brands, provided they are same size and rank, which is useful to know if you cannot obtain sticks that are 100% identical to two sticks you already have.
Note this is contrary to the common understanding that slots 1 and 3 must be identical, and slots 2 and 4 must be identical.
So glad I googled "memory upgrade problems imac 2020" BEFORE I ordered additional memory for my new iMac!
Thanks to all who have posted their experiences. I was originally going to order 16GB to add to my 8GB, so now need to decide if I want to spend a couple extra bucks and order 32GB.... OR go cheap and try two aftermarket 4GBs. 16GB is probably really need, so I COULD just shelve the OEM 8GB like most people here have suggested. Another option would to be to buy removed Apple 4gb sticks from someone here just to run the experiment to see if two diffferent pairs of Apple 4gb memory work properly together.
Hmmmm.....buy the RAM amount I really want and be done with it? Or spend less initially just so I can experment, report the results here to satisfy some curiosity, and ultimately probably have to re-buy more to get it to work right?
Thanks to all who have posted their experiences. I was originally going to order 16GB to add to my 8GB, so now need to decide if I want to spend a couple extra bucks and order 32GB.... OR go cheap and try two aftermarket 4GBs. 16GB is probably really need, so I COULD just shelve the OEM 8GB like most people here have suggested. Another option would to be to buy removed Apple 4gb sticks from someone here just to run the experiment to see if two diffferent pairs of Apple 4gb memory work properly together.
Hmmmm.....buy the RAM amount I really want and be done with it? Or spend less initially just so I can experment, report the results here to satisfy some curiosity, and ultimately probably have to re-buy more to get it to work right?
IMO, the most cost-effective option (i.e best value for your money, not the cheapest option) is buy 2x16GB sticks (preferably one of the brands listed at the beginning of the "Memory Upgrade Compatibility" thread), and toss the 2x4GB Apple sticks. And be done with it. In the event you later need more than 32GB (unlikely for most people), it is possible to later add another 2x16GB, which keeps your options open.So glad I googled "memory upgrade problems imac 2020" BEFORE I ordered additional memory for my new iMac!
Thanks to all who have posted their experiences. I was originally going to order 16GB to add to my 8GB, so now need to decide if I want to spend a couple extra bucks and order 32GB.... OR go cheap and try two aftermarket 4GBs. 16GB is probably really need, so I COULD just shelve the OEM 8GB like most people here have suggested. Another option would to be to buy removed Apple 4gb sticks from someone here just to run the experiment to see if two diffferent pairs of Apple 4gb memory work properly together.
Hmmmm.....buy the RAM amount I really want and be done with it? Or spend less initially just so I can experment, report the results here to satisfy some curiosity, and ultimately probably have to re-buy more to get it to work right?
I ordered 2x16GB sticks from OWC. When I saw that Apple ram and 3rd party wasn't working together, I ordered another 2x16GB from OWC. The ram arrived and looks different; apparently two different manufactures. One made in Mexico and the other Taiwan. Since they came all the way from the US to Australia, I decided to try them together. Slots 1,3 Mexico and 2,4 Taiwan dropped speed to 2133MHz. I put them in slots 1,2 and 3,4 and speed is up to 2666MHz.
Attached are a few screenshots. Does this look OK, or should I return some or all of the RAM for something else or try with 32GB?
Attached are a few screenshots. Does this look OK, or should I return some or all of the RAM for something else or try with 32GB?
Attachments
Thanks for testing this out! So the general consensus is that dual channel is working here? I had suspected that running a pair of sticks in each channel would work provided all are the same size - if so that's good news for me, all I need to do is buy another set of 16GB sticks next time I need to upgrade.
That’s why I strongly dislike OWC. They don’t have a single Bill Of Materials like Kingston or Crucial. When Kingston and Crucial (even more) create a model, you are sure the same model in 3 years will have the same DRAM chips. OWC is a whore to which DRAM chip is the cheapest, like Corsair and other “good known brands”.
Mexico = Micron chip
Taiwan = Hynix chip
Probably one week Micron was cheaper... ?♂️
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I'm sure you are right on this, and had I known I would have purchased different RAM, but if you look at the screenshots I posted above, does it look like my numbers are where they should be for an i7 with the 5500xt? Am I better off to run 32GB? I am in Australia so exchanging it will be somewhat costly and time consuming.
Another data point:
I have the 10 core 5700xt system.
I ordered 128GB from OWC and received two packs of 2 x 32GB DIMMs.
Each pair is matched, but the two packages contain different memory (they look physically different). Putting Package 1 DIMMs in 0 2 and Package 2 DIMMs in 1 and 3 as recommended resulted in 2133MHz. Putting Package 1 in 0 1 and Package 2 in 2 3, resulted in the expected 2667mhz.
Novabench says RAM Speed: 29935 MB/s
That sounds like expected speeds, right? Thanks!
I have the 10 core 5700xt system.
I ordered 128GB from OWC and received two packs of 2 x 32GB DIMMs.
Each pair is matched, but the two packages contain different memory (they look physically different). Putting Package 1 DIMMs in 0 2 and Package 2 DIMMs in 1 and 3 as recommended resulted in 2133MHz. Putting Package 1 in 0 1 and Package 2 in 2 3, resulted in the expected 2667mhz.
Novabench says RAM Speed: 29935 MB/s
That sounds like expected speeds, right? Thanks!