Notebook Hardware and Upgrade Questions

Dear all, 

I recently bought and installed a further 8Gb ram bank on my HP Laptop 15-bs0xx. If I checked the specifics correctly I should have bought the right one (DDR4, 2133MHz, SODIMM, 260pin). 

After plugging in the component, I noted that the task manager, even after various restarts, was not yet able to detect the new component. Therefore, I checked on CPU-Z software and found the following situation: 

- The SPD panel shows that both the ram slots are occupied and I can see the specifics of each of it.

- The memory panel recognizes that the total memory amounts to 16 Gb (so 8Gb times 2 components). Nevertheless, the same panel also reports that the memory channel is single and not double as it would be needed to make use of both the components. 

After looking for more information on this community, I checked also the mantainance and service manual of my laptop model and it actually says the pc should be able to support dual channel ram. 

Here I paste the link http://h10032.www1.hp.com/ctg/Manual/c05493257

Subsequently, I started to look information to discover whether is it possible to switch manually the memory to dual channel mode and it seems like that something could be done on the BIOS... but I really did not find any trusted or exhaustive guide which describes the procedure. 

Can anybody help me with this issue? I am not a computer scientist or whatever, so I may have done some errors throughout all these procedures. Any help is really appreciated. 

cheers, 

Matteo