Dual Socket Motherboards & RAM Module Placement

[kenkanif]

So I just bought a Dell PowerEdge 2950 to tinker with, it came with one CPU and I just bought a different matching pair on EBay along with new RAM. When putting this RAM in, do I have to place it in specific banks for both processors to each get their own? Ive never dealt with something like this before but I've been reading some things that lead me to believe this is the case.

The hardware owners manual doesn't specifically talk about the placement of RAM when using dual CPU's so I'm not really sure.

Thanks in advance!

 

[noidea_77]

The manual on page 89 describes the channel concept and witch socket belongs to witch channel. You will get the best performance from adding four stick, one per channel (1,2,3,4 or 5,6,7,8,)

 

[kenkanif]

That page does not speak of sockets, aside from the RAM sockets. It talks about two branches, and each branch having two channels. Does each branch belong to a CPU socket?

 

[Wisecracker]

Each CPU socket has its own DIMM bank. Each DIMM bank has quad-channel capability.

 

[kenkanif]

So could you be more clear on how those banks are divided between the processors? In the manual it refers to branches which is a term I haven't heard before, is each branch assigned to each CPU socket?

What I plan on doing right now based on what I gather is to place a ram module in slots 1 and 5, 3 and 7. This would place two sticks on branch 0, channel 0, and two sticks in branch 1, channel 2.

 

[kenkanif]

If it helps to know what im basing this off of, I am reading the hardware manual mentioned above, page 89.

ftp://ftp.dell.com/Manuals/all-products/esuprt_ser_stor_net/esuprt_poweredge/poweredge-2950_owner%27s%20manual_en-us.pdf

 

[k1114]

You put them in 1,2,3,4. That puts 1 stick per channel so you utilize all channels. The manual states "sockets must be populated by lowest number first."

 

[kenkanif]

Yeah I saw that, the only thing was that the old RAM modules were not placed like that, which made me think there was more to it than just sticking them in there. It makes sense though as far as dual channel is concerned.

 

[kenkanif]

Just put in the new sticks and realized the banks weren't in numerical order. Silly me. So yeah the previous modules were in the 1234 slots, as are the new ones.

Another question would be why, since I bought the server with one CPU, were the sticks in 1234 banks, wouldn't that mean that half of it was going to a non-existent CPU or am I not understanding this correctly?

 

[k1114]

The ram controller is on the mobo so will control it all. Ram should be in every other slot.

 

[noidea_77]

As k1114 said, this is an old server with the memory controller in the chip set. Only new cpus have there own memory controllers.

 

[kenkanif]

Awesome thank you. Makes sense.