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I just purchased two 8GB Ram sticks which are packaged at 1866Mhz - my system only supports 1600MHz, so I was expecting them to run at this speed.

But when I examine the output of dmidecode, it reports Speed: 1333 MHz and Configured Clock Speed: 1600 MHz. (Where as the existing 4GB stick is running at 1600). Should this be expected? Is there a reason it would be 1333 rather than 1600?

sudo dmidecode --type memory
# dmidecode 3.0
Getting SMBIOS data from sysfs.
SMBIOS 2.7 present.

Handle 0x003D, DMI type 16, 23 bytes
Physical Memory Array
    Location: System Board Or Motherboard
    Use: System Memory
    Error Correction Type: Single-bit ECC
    Maximum Capacity: 32 GB
    Error Information Handle: Not Provided
    Number Of Devices: 4

Handle 0x003E, DMI type 17, 34 bytes
Memory Device
    Array Handle: 0x003D
    Error Information Handle: Not Provided
    Total Width: 72 bits
    Data Width: 64 bits
    Size: 8192 MB
    Form Factor: DIMM
    Set: None
    Locator: DIMM3
    Bank Locator: Not Specified
    Type: DDR3
    Type Detail: Synchronous
    Speed: 1333 MHz
    Manufacturer: Micron
    Serial Number: 0EF0CD0AC012
    Asset Tag: 15162000
    Part Number: 18JSF1G72AZ-1G9P1 
    Rank: 2
    Configured Clock Speed: 1600 MHz

Handle 0x0040, DMI type 17, 34 bytes
Memory Device
    Array Handle: 0x003D
    Error Information Handle: Not Provided
    Total Width: 72 bits
    Data Width: 64 bits
    Size: 4096 MB
    Form Factor: DIMM
    Set: None
    Locator: DIMM1
    Bank Locator: Not Specified
    Type: DDR3
    Type Detail: Synchronous
    Speed: 1600 MHz
    Manufacturer: Hynix/Hyundai
    Serial Number: 0AF08C05F080
    Asset Tag: 01144100
    Part Number: HMT451U7AFR8A-PB  
    Rank: 1
    Configured Clock Speed: 1600 MHz

Handle 0x0042, DMI type 17, 34 bytes
Memory Device
    Array Handle: 0x003D
    Error Information Handle: Not Provided
    Total Width: 72 bits
    Data Width: 64 bits
    Size: 8192 MB
    Form Factor: DIMM
    Set: None
    Locator: DIMM4
    Bank Locator: Not Specified
    Type: DDR3
    Type Detail: Synchronous
    Speed: 1333 MHz
    Manufacturer: Micron
    Serial Number: 07E0CE0AC012
    Asset Tag: 15162000
    Part Number: 18JSF1G72AZ-1G9P1 
    Rank: 2
    Configured Clock Speed: 1600 MHz

Handle 0x0044, DMI type 17, 34 bytes
Memory Device
    Array Handle: 0x003D
    Error Information Handle: Not Provided
    Total Width: Unknown
    Data Width: Unknown
    Size: No Module Installed
    Form Factor: DIMM
    Set: None
    Locator: DIMM2
    Bank Locator: Not Specified
    Type: Unknown
    Type Detail: None
    Speed: Unknown
    Manufacturer: [Empty]
    Serial Number: [Empty]
    Asset Tag: 00000000
    Part Number: [Empty]
    Rank: Unknown
    Configured Clock Speed: Unknown
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  • We're going to need to know a lot more about your system; make and model of motherboard and CPU/s for a start. – Chopper3 Aug 23 '16 at 9:12
  • 1
    It's a Dell Poweredge T20 - Intel C226 chipset: i.dell.com/sites/doccontent/shared-content/data-sheets/en/… – Dan Poltawski Aug 23 '16 at 9:14
  • What's you're bios say about all this? The OS isn't the best place to check. – Ryan Babchishin Aug 23 '16 at 9:54
  • I've been looking into this for a bit too long now and I have literally no idea what's going on - certainly the server supports 1600, as does your memory, though sometimes the more modules you add the slower it can go - test the system with a single module in - see if that changes anything. There is also a small chance that your 1866 memory is somehow not being handled correctly by the BIOS. – Chopper3 Aug 23 '16 at 10:39
  • The Dell bios doesn't have any memory 'options' as far as I can see, and only mentions 1600 – Dan Poltawski Aug 23 '16 at 10:45
3

You're operating both new models on the same channel (and the old module on the other channel, which Intel calls "Flex Memory", but that shouldn't directly impact timings on the other channel.) Some mainboard/CPU/RAM combos don't like that (and in fact I know of some Supermicro boards where they even specify lower speed for two-DIMMS-populated-per-channel configurations in their manuals, but I couldn't find that in your server's manual) and that may lead to slower timings being picked. Try removing one of the 8GB sticks to see if the other one reaches 1600 in that case.

Since the memory probably isn't on Dells compatibility list for your system there is unfortunately little you can do.

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  • I tried various combinations of taking the RAM out and unfortunately it made no difference. Always ended up clocked at 1333 – Dan Poltawski Aug 24 '16 at 9:44
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It might be that you need to overclock it yourself (either manually or via XMP if it is supported) to 1600mhz in the bios, since by default most memory runs at 1333mhz.

This is because your cpu typically won't need more. Even if you can't get it enabled it's not that bad because you won't see much difference, or maybe even none.

Here is a more detailed explanation: http://www.tomshardware.co.uk/forum/321367-31-ddr3-memory-running-1333mhz-rated-1600mhz#5281588

side note; keep in mind that the slowest clocked memory will typically slow down other memory as well to the same speed.

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  • 3
    Neither manual OCing nor XMP is supported in C226 as it is a server platform. – maxf Aug 23 '16 at 10:59

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