iMac 5K 27" RAM speed discrepancy?

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iMac Intel 27" Retina 5K Display (Late 2014 & 2015)

Model A1419 / EMC 2806 / Late 2014 or Mid 2015. 3.3 or 3.5 GHz Core i5 or 4.0 GHz Core i7 (ID iMac15,1); EMC 2834 late 2015 / 3.3 or 3.5 GHz Core i5 or 4.0 GHz Core i7 (iMac17,1) All with Retina 5K displays

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Rasmus Jacobsen @rasmus90

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Postado: 2 de ago de 2019

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iMac 5K 27" RAM speed discrepancy?

Hi,

Yet again I’m confused – and I hope you can help me.

I recently bought a 5K 27” iMac late-2015. I have just upped the RAM with 16GB of 1867 MHz 204-pin SODIMMs Apple specifies through their website. So now my total is 24GB of RAM. But upon installing it still says 1600 MHz in ‘about my mac’ – how can that be?

Is it possible me make the iMac “think” it is a newer machine - I bought it via ebay, so I’m a bit afraid of the deal being a swindle.

I’ve included a screenshot of Apples RAM recommendations and about my mac.

The system report of memory:

BANK 0/DIMM0:

Størrelse: 4 GB

Type: DDR3

Hastighed: 1600 MHz

Status: OK

Producent: 0x80AD

Produktnummer: 0x484D54343531533642465238412D52442020

Serienummer: 0x25581852

BANK 0/DIMM1:

Størrelse: 8 GB

Type: DDR3

Hastighed: 1600 MHz

Status: OK

Producent: 0x198

Produktnummer: 0x4B4858313836364331352F38472020202020

Serienummer: 0x35701602

BANK 1/DIMM0:

Størrelse: 4 GB

Type: DDR3

Hastighed: 1600 MHz

Status: OK

Producent: 0x80AD

Produktnummer: 0x484D54343531533642465238412D52442020

Serienummer: 0x25131812

BANK 1/DIMM1:

Størrelse: 8 GB

Type: DDR3

Hastighed: 1600 MHz

Status: OK

Producent: 0x198

Produktnummer: 0x4B4858313836364331352F38472020202020

Serienummer: 0x35701602

Thank you!

Rasmus

EDIT:

I’ve taken a picture of all the RAM modules. If it can help :)

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Dan @danj

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Postado: 2 de ago de 2019

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Pull your 4 GB modules and then check again. I think what you are seeing is the slower modules are running at 1600 so your faster modules (1867 MHz) need to run at the slower clock.

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Thank you! Do you think the existing ones are 1600 MHz and this keeps a lid on the newer ones. So if I pul the slower ones out, I might see the faster clock of 1867 MHz?

2 de ago de 2019 por Rasmus Jacobsen

Give it a try

3 de ago de 2019 por Dan

Hi Dan, I just tried your method - even restarted the machine several times with the 4 GB modules out in hopes of it working - it didn't work. It still showed 1600 MHz.

Is it possible I have received bad RAM modules and the ones installed in the computer are also underpowered? The only way I can test this would be to purchase even more RAM modules from another seller.

Is there some "BIOS" upgrade I've missed?

Thank you again!

Rasmus

p.s. I've taken a picture of the installed RAM modules. It's in the original post.

3 de ago de 2019 por Rasmus Jacobsen

Had a friend of mine check his system (he has a a '15 model as well) it turns out this series memory bus is fixed at 1600 which is why your newer 1867 RAM is not able to run at its clock. There is no BIOS (EFI) alterations possible in Apple systems unlike Windows PC which some allow over-clocking.

3 de ago de 2019 por Dan

Hi Dan,

Your friend must have a mid-2015 version, which Apple states have an 1600 MHz clock speed

(https://support.apple.com/kb/SP718?viewl...)

but the late-2015 should have the 1867 clock speed (https://support.apple.com/kb/SP731?local...) Somehow the machine doesn’t register the correct clock speed.

Maybe it’s not that important, but I see it as a stone in my shoe, and I just don’t understand why if the computer has not been “tampered” with.

How do an iMac know what version it is – this must be changeable – and after this the computer will become more valuable?

Rasmus

4 de ago de 2019 por Rasmus Jacobsen

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Thank you! Do you think the existing ones are 1600 MHz and this keeps a lid on the newer ones. So if I pul the slower ones out, I might see the faster clock of 1867 MHz? — Rasmus Jacobsen
Hi Dan, I just tried your method - even restarted the machine several times with the 4 GB modules out in hopes of it working - it didn't work. It still showed 1600 MHz.

Is it possible I have received bad RAM modules and the ones installed in the computer are also underpowered? The only way I can test this would be to purchase even more RAM modules from another seller.

Is there some "BIOS" upgrade I've missed?

Thank you again!

Rasmus

p.s. I've taken a picture of the installed RAM modules. It's in the original post. — Rasmus Jacobsen
Had a friend of mine check his system (he has a a '15 model as well) it turns out this series memory bus is fixed at 1600 which is why your newer 1867 RAM is not able to run at its clock. There is no BIOS (EFI) alterations possible in Apple systems unlike Windows PC which some allow over-clocking. — Dan
Hi Dan,

Your friend must have a mid-2015 version, which Apple states have an 1600 MHz clock speed

(https://support.apple.com/kb/SP718?viewl...)

but the late-2015 should have the 1867 clock speed (https://support.apple.com/kb/SP731?local...) Somehow the machine doesn’t register the correct clock speed.

Maybe it’s not that important, but I see it as a stone in my shoe, and I just don’t understand why if the computer has not been “tampered” with.

How do an iMac know what version it is – this must be changeable – and after this the computer will become more valuable?

Rasmus — Rasmus Jacobsen

iMac Intel 27" Retina 5K Display (Late 2014 & 2015)

iMac 5K 27" RAM speed discrepancy?

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