Our controller is only 40-bit, But we need to support 80-bit with 10x DDR4/DDR3 , how to realize it?

Background:

In terms of 8TB SSD, the bottle neck is the DDR which is illustrated as below:

a. The biggest wide temp DDR is 1GB x 8bit 

b.8TB SSD needs 10pcs 1GB DDR(with pECC) on boards

c.80bit DDR as maximum but our controller only support 40bit DDR (DDR_DQ0~DDR_DQ39)

Question:  How to realize the requirement?

1, Is there any dual channel DRAM controller or solution recommended to meet it?

2, Does the controller either need 80-bits or it needs more CS (Chip Select) or a combination of Address+BA+BG signals to select the new set of 5x DDR4 chips?

3, Currently the controller only has 2x CS -- and this is where the problem comes from. Additional problems are due to the extra load and branching on the Address and DATA. how to deal with it?

Regards,

David Hu