I MIGHT HAVE UNDERESTIMATED....

[TrevorH]

Dell EMC PowerEdge R740xd Installation and Service Manual | Dell United Kingdom

 

[RolloZ170]

quick question. if I populate the additional mem slots (black) does memory speed drop to 2666?

not sure, depends on BIOS programmer.
from intel side not. e.g. supermicro's X11 w. 2nd gen scalable do not decrease speed in 2DPC config.

 

[Whaaat]

2nd gen scalable do not decrease speed in 2DPC config.

they do

 

[RolloZ170]

they do

it is always the BIOS doing this. manual states no speed change from 1DPC too 2DPC with 2933 RAM.

 

[Whaaat]

manual states no speed change from 1DPC too 2DPC with 2933 RAM.

yep, mobo typically doesn't care, it's processor thing to decide

 

[RolloZ170]

yep, mobo typically doesn't care, it's processor thing to decide

doubt that. CPU does not know how much speed the RAM can. BIOS code reads the SPD.
with std. AMI BIOS you can disable enforce POR to keep speed if BIOS usualy downgrades speed.

 

[Whaaat]

CPU does not know how much speed the RAM can

But it knows how much speed it will do with 2DPC anyway)

 

[RolloZ170]

But it knows how much speed it will do with 2DPC anyway)

...if nobody cares. or usualy decide based on POR.
you sayd

they do

what now ?

 

[Whaaat]

what now ?

now mobo vendors can abuse it by ignoring this limitation when and only when you install validated RAM (HP smart memory in HP, TrueDDR4 in Lenovo and so on...)

 

[RolloZ170]

now mobo vendors can abuse it by ignoring this limitation when and only when you install validated RAM (HP smart memory in HP, TrueDDR4 in Lenovo and so on...)

not sure, depends on BIOS programmer.
from intel side not. e.g. supermicro's X11 w. 2nd gen scalable do not decrease speed in 2DPC config.

 

[Whaaat]

ok, so Dell R740 grants intel specs, what now?

 

[RolloZ170]

ok, so Dell R740 grants intel specs, what now?

2nd gen scalable do not decrease speed in 2DPC config.

they do

 

[oddssodds]

So it does on second gen cpu? In mexico and if I can just add 16 gb sticks, much easier

 

[RolloZ170]

So it does on second gen cpu?

unclear. 2nd gen can hold speed in 2DPC. but vendors BIOS must play with you.

 

[oddssodds]

unclear. 2nd gen can hold speed in 2DPC. but vendors BIOS must play with you.

So the test is to pull two of the ram sticks from processor two and install them in the black slots of processor one and see if the speed drops?

 

[RolloZ170]

So the test is to pull two of the ram sticks from processor two and install them in the black slots of processor one and see if the speed drops?

2DPC in a supported configuration.

 

[oddssodds]

2DPC in a supported configuration.

Wood moving two DIMM to the first CPU 1 an unsupported configuration?

 

[RolloZ170]

Wood moving two DIMM to the first CPU 1 an unsupported configuration?

unknown. i don't know your RAM population. but the manual should help you.
population must be balanced. but you normaly can run CPU2 without any RAM.
edit
In a dual-processor configuration, the memory configuration for each processor must be identical

 

[oddssodds]

unknown. i don't know your RAM population. but the manual should help you.
population must be balanced. but you normaly can run CPU2 without any RAM.

Currently every white socket has a 16 GB stick in it.

I want to run an LLM with experts cashed to memory on CPU one, but 96 isn’t enough space

 

[RolloZ170]

Currently every white socket has a 16 GB stick in it.

A1 - A7
A4 - A10

B1 - B7
B4 - B10
remove all other and check RAM speed