2133 MHz shows up as 1866 MHz on Supermicro board

[trumee]

Hello ,

I have Micron 36ASF2G72PZ-2G1B1 ram sticks in X10DriT motherboard. It supports 2133MHz but it shows up as lower speed of 1866 MHz. Any idea what could be the issue?

Sample dmidecode,

Handle 0x0075, DMI type 17, 40 bytes
Memory Device
Array Handle: 0x006D
Error Information Handle: Not Provided
Total Width: 72 bits
Data Width: 72 bits
Size: 16 GB
Form Factor: DIMM
Set: None
Locator: P2_DIMMF2
Bank Locator: P1_Node1_Channel1_Dimm1
Type: DDR4
Type Detail: Synchronous
Speed: 2133 MT/s
Manufacturer: Micron
Asset Tag: P2_DIMMF2_AssetTag (Date:16/22)
Part Number: 36ASF2G72PZ-2G1B1
Rank: 2
Configured Memory Speed: 1866 MT/s
Minimum Voltage: Unknown
Maximum Voltage: Unknown
Configured Voltage: Unknown

 

[RolloZ170]

if your CPU supports only 1866 the memory will run at this.

 

[alex_stief]

Could be a lot of things...
Some CPUs for this board support DDR4-1866 maximum.
The memory speed might be set to auto, and the board clocks it down because of too many ranks per channel.
Or memory speed is just set to DDR4-1866 in bios.

 

[NablaSquaredG]

How many DIMMs do you use?

2 DIMMs per Channel (more than 4 per CPU) with Xeon E5 v3 -> 1866 instead of 2133

 

[trumee]

The memory speed might be set to auto, and the board clocks it down because of too many ranks per channel.

The memory speed in the BIOS is indeed set to auto. The CPU is E5-2650 v4 which does support 2133.

The manual has this documentation,








I have 16GBx8 sticks. Is there any order i should follow to get 2133MHz?

 

[RolloZ170]

I have 16GBx8 sticks. Is there any order i should follow to get 2133MHz?

2 RDIMMs per channel:
if enforce POR is set in BIOS the mem.speed is lowered to 1866

 

[NablaSquaredG]

2 RDIMMs per channel:
if enforce POR is set in BIOS the mem.speed is lowered to 1866

But not for v4. v4 2 DPC -> 2133

 

[RolloZ170]

But not for v4. v4 2 DPC -> 2133

imho the BIOS does not differentiate between V3 and V4.
see the following SM FAQ, other mboard but a hint.

FAQ Entry | Online Support | Support - Super Micro Computer, Inc.

Frequently Asked Questions

www.supermicro.com

 

[trumee]

I moved the memory from A1/A2/B1/B2, D1/D2/E1/E2 to slots A1/B1/C1/D1/E1/F1/G1/H1. These are all the blue slots on the motherboard. The memory showed up as 2133MHz.

Is that the preferred way of setting up memory i.e. blue slots first followed by black slots?

 

[RolloZ170]

Is that the preferred way of setting up memory i.e. blue slots first followed by black slots?

of course. black slots are secondary slots. A2 is a´same channel than A1.
A1 B1 C1 D1 are the main channels of CPU0.

 

[RolloZ170]

if you populate 8 more RDIMMs (blue AND black) and the BIOS reduces to 1866, disable "enforce POR" (should be there in your BIOS)

 

[alex_stief]

Congratulations, you just increased the available memory bandwidth by more than a factor of 2