Multi (memory)-channel Xeons - Speed vs number of populated channels?

[Ulf_K]

I recently acquired a Z6 G5 with a W9-3475X and 128GB RAM. Only four memory channels are populated using 32GB DDR5 RAM. Now, this model has 8 channels in total so 4 are presently not in use. I will not need another 128 GB (at the moment).

My question is: How "aware" is the CPU of not using half of its memory bandwidth? Does this configuration slow down memory access (in total). Is the CPU capable of acheiving the same memory transfer speed using only half its bandwidth or should I for the sake of overall processing speed invest in 4 more sticks (~$ 200 each...)

[SDH]

You'll want to read up on your memory configuration and optimization in the Technical Whitepaper from HP for the Xeon W versions of the Z6 G5, attached below. For those interested in the hotter running AMD variant of the workstation (the Z6 G5 A) there is a similar Whitepaper that is easy to find via google.

Nothing that money can't fix...

[DGroves · Accepted solution]

this question is a !CLASSIC REASION! my company always recommended to clients

DETERMINE THE SOFTWARE THAT WILL BE USED,

then use that information to determine what hardware to buy/use/configure

memory bandwidth usage is very application dependent, so your question really can't be answered other than to say having excessive/unused mem bandwidth will not hurt performance................just your pocketbook