Chip Density on same speed of RAM can cause 20% of Performance difference!

Simonsayz

Active member
Feb 17, 2014
263
72
33
Islamabad
TLDR; Difference of performance between two RAMs of same Capacity / Speed / Timing & Latency but different Chip Density can be upto 20%, with Higher Density RAMs being the source of bottleneck. For details, read below.

Saw LTT's latest video and was dumbfounded that these guys didn't know Memory Rank or RAM Chip Density is a thing. It's right there in every RAM stick's specs, you need to check rank/density when buying RAM, it can cause incompatibility between RAM sticks or performance bottlenecks. To be fair to them, it's not mentioned in most Laptop specs by OEMs, although, somehow same OEMs mention Rank/Density in their Desktop builds.

RAM Basics

JDEC DDR4 Standards

How to read RAM Label
RAM.jpg

Memory Rank
Memory Rank means the RAM Chips on the particular RAM stick will appear as one group, two groups and so on, to the system. It is marked on the RAM specs as 1R, 2R..., where 1R = Single Rank, 2R = Dual Rank and so on.

RAM Chip Density
Chip Density is marked along with Memory Rank e.g., 1Rx8 or 1Rx16
where x8 = 8bit Density and x16 = 16bit Density

(Non-ECC) DDR memory is always accessed as 64bits wide data by the system. So, on a Single Rank (1R) RAM, to get a 64 bit wide rank, you need Number of Chips on a RAM Stick and the Chip Density to correlate to 64.

____64____ = Number of Chips on RAM Stick
Chip Density

For an 8GB RAM stick with x8 ( 8bit density), it needs to have 8 chips (64/8 =8).
For an 8GB RAM stick with x16 (16bit density), it needs to have 4 chips (64/16=4).

As Chip Density increases, there is less number of memory chip modules on a RAM stick but those chips are of higher capacity and higher density.

For example,
8 GB RAM stick of "1Rx8" means 8 chips on one stick, means each chip is of 1GB.
8 GB RAM stick of "1Rx16" means 4 chips on one stick, means each chip is of 2GB.

Effect of Chip Density
This is why we are here, less number of chips means lesser interacts available between CPU & RAM, hence performance decline due to RAM bottleneck.

FYI
A RAM Module with chips on one side of the PCB is called single-sided.
A RAM Module with chips on both sides of the PCB is called dual-sided.
A RAM module with chips on one side (single-sided) of the PCB, could still be single-ranked, dual-ranked, or quad-ranked.
A RAM module with chips on both sides (dual-sided) of the PCB, could still be single-ranked, dual-ranked, or quad-ranked.

On to the benchmarks




 
General chit-chat
Help Users
We have disabled traderscore and are working on a fix. There was a bug with the plugin
  • No one is chatting at the moment.
    manigamer manigamer: leon is a clusterfuck other than that the actors were decent. chris was fine, albert looked...