PowerEdge Hardware General

Last reply by 04-27-2021 Solved
Start a Discussion
2 Jasper
2 Jasper
735

R820 RAM 1866 Mhz running at 1333 Mhz

Hi,

I have a R820 equipped with 4 x E5-4627 v2.

I installed 48x32Gb RAM to attempt the max of 1.5Tb. 

The RAM I'm using is JGGRT:  Pc3-14900 DDR3-1866 mhz.

When I boot the machine I'm getting RAM running at 1333 instead 1866.

The CPU, as I found in intel website, supports 1866 Mhz.

Can someone tell me what I'm missing?

Thank you.

Solutions (3)

Accepted Solutions
584

Abidal,

 

Even with the CPU supporting the dimms, it is limited at the server. With 3 LR dimms populated in the same channel, the server limits 1.5v dimms to 1333. You can see this on page 46 of the manual here

 

Let me know if this helps.

 

 


Chris Hawk
Social Media and Communities Professional
Dell Technologies | Enterprise Support Services
#Iwork4Dell

Did I answer your query? Please click on ‘Accept as Solution’
‘Kudo’ the posts you like!

View solution in original post

579

Hello,

 

You have achieved the maximum supported performance at 1333 MHz. The limiting factor is the LRDIMMs per this chart on page 46 of the manual Chris linked.

 

 

This second chart shows that the config you have is supported, but they will operate at the lower 1333MHz speed.

 

#Iwork4Dell

View solution in original post

563

Hi Abidal,

 

That clock speed should be perfectly fine, especially since the rest of your memory is already being downclocked to match. You'll want to make sure other characteristics match though, such as rank and type of DIMM (LRDIMM, RDIMM, or UDIMM, for example).

#Iwork4Dell

View solution in original post

Replies (12)
2 Jasper
2 Jasper
608

PS: Bios, iDRAC and LC updated.

585

Abidal,

 

Even with the CPU supporting the dimms, it is limited at the server. With 3 LR dimms populated in the same channel, the server limits 1.5v dimms to 1333. You can see this on page 46 of the manual here

 

Let me know if this helps.

 

 


Chris Hawk
Social Media and Communities Professional
Dell Technologies | Enterprise Support Services
#Iwork4Dell

Did I answer your query? Please click on ‘Accept as Solution’
‘Kudo’ the posts you like!
581

Hi Chris,

Thank you for replying, even I didn't understand well.

The fact is that I have 48 RAM 1866. What to do to get the max performance?

Thank you in advance.

580

Hello,

 

You have achieved the maximum supported performance at 1333 MHz. The limiting factor is the LRDIMMs per this chart on page 46 of the manual Chris linked.

 

 

This second chart shows that the config you have is supported, but they will operate at the lower 1333MHz speed.

 

#Iwork4Dell
572

Hi Dylan,

Please, I'm asking you to be patient:

Should I understand that putting 1866 or 1333 RAM I will get the same performance?

Second thing, what can be the best mode to use in my case (Advanced ECC, sparing, ...)?

Thank you in advance.

570

Apologies if that seemed impatient, I was only looking to be concise

 

To answer your question, in your case, yes, you won't see any difference between 1866 MHz and 1333 MHz DIMMs because they'd just get downclocked by the system to 1333 MHz. 

 

As to the mode, that's a little harder to answer. It really comes down to what features you need. Most people stick with the optimized configuration. If this were a database server, something like advanced ECC could be appropriate. If you can share some detail on what you're looking for with the server, I may be able to make a better recommendation. 

#Iwork4Dell
569

Hi Dylan,

Thank you for technical details.

I want to use this server with ESXi. I want install windows server VM for traditional use (DNS, AD ...) but especially to run an ERP based on MS SQL Server (10-15 client users).

That a concise description of my projects.

 

568

I'd personally stick with the optimized config. The Advanced ECC option tends to be for, at least from what I've seen, really large databases. Optimized is also the only config where you'll see all of the memory you've installed. If you switch to another mode, you'll see the usable memory decrease. 

 

If I were to boil it down though, advanced ECC would be there to protect you from a multibit memory error on a DIMM, which could crash a server. This would give you a more reliable uptime, but the cost would be reduced memory availability. Memory sparing and memory mirroring both offer a similar benefit of increased protection, but the memory cost associated with that does increase.

 

EDIT: What you might consider is setting the system in the optimized config so that all of your memory space is available, then observing how much of that gets used when the system is under load. Once you can establish a baseline for what your implementation is using, you could then take that information and potentially change the mode to offer greater protection.

#Iwork4Dell
565

Hi Dylan,

It's clear for me now.

I'm really thankful for all technical details you provided.

Have a nice day.

Latest Solutions
Top Contributor