Keep in mind the Channel when adding new RAMs in sockets

The Dell PowerEdge T420 server has 12 DIMM slots. For optimal performance, it is recommended to install RAM in pairs of matching capacity and speed.

We already have two 4 GB models placed in white DIMMS.  We added two more so keep in mind the number that is mentioned on the motherboard DIMMS places. The system contains 12 memory sockets split into two sets of six sockets, one set per processor. Each six-socket set is organized into three channels. In each channel, the release levers of the first socket are marked white and the second black.

NOTE: DIMMs in sockets A1 to A6 are assigned to processor 1 and DIMMs in sockets B1 to B6 are assigned to processor 2.

Figure 35. Memory Socket Locations find PowerEdge-t420_owners-manual_en-us page# 69

RAM channels, specifically dual-channel and quad-channel memory configurations, are used to improve memory bandwidth and overall system performance. These configurations are commonly employed in both consumer and server systems. Here's why RAM channels are used and their purposes:

VERY CLOSER LOOK OF RAM S0CKET NUMBER  on Motherboard Dell 420 PowerEdge

Figure 35. Memory Socket Locations

 Processor 1

• channel 1: memory sockets A1 and A4      
• channel 2: memory sockets A2 and A5
• channel 3: memory sockets A3 and A6

Processor 2

• channel 1: memory sockets B1 and B4
• channel 2: memory sockets B2 and B5
• channel 3: memory sockets B3 and B6

This is the wrong setting. Not According to the Channel configuration but RAM is shown as 16 GB

Wrong Arrangement of RAM in the RAM Socket(A1,A2,A3 and A4)

Image with Socket Number on Motherboard Dell 420 PowerEdge

Why is the RAM according to the channel setting

The purpose of RAM channels is to increase the bandwidth between the CPU and RAM. This can improve the performance of memory-intensive applications, such as video editing, gaming, and 3D rendering.

This is the Right setting.  According to the Channel configuration, RAM is shown as 16 GB.

Correct installation of RAM according to the channel1(A1+A4) and channel1(A2+A5)