Unsure how much memory I can upgrade my Slimline 290 to

[Inlander]

The specs are confusing re memory upgrades for my 64-bit OS.  It says 4GB is already (factory) installed, and indicates that

• there are 2 slots for memory cards,
• they can support 4 or 8GB DDR-4's,
• the max memory supported (64-bit) is 8GB

This is confusing.

1. If there is already 4GB installed, is that one of the slots?
2. If the max is 8GB, is that 2x4GB more, or just one more 4GB (i.e., is the 8GB max how much additional can be added, or is it total, so only 4GB can be added)?
3. Does memory have to be added in even doubles, such as 2 cards x 4GB or 2 x 8GB.

There is more I would like to ask, but I need to understand the above first.

TIA for any help you can give

[banhien]

@Inlander 

What is your Slimline 290 ?  One example HP Slimline 290-p0014, its specs (which shows some confusions, should be 16GB (2 x 8GB)):

     https://support.hp.com/au-en/document/c06066476

Your machine probably has same motherboard and you can upgrade to 16GB using  (or similar):

           https://www.crucial.com/memory/ddr4/ct2k8g4dfs824a/ct13106806

Regards.

[Inlander]

It's a 290-p0043w, and the specs are as follows:

Memory

• 4 GB
• Amount: 4 GB
• Speed: PC4-19200 MB/s
• Type: DDR4-2400

Memory upgrade information

• Dual channel memory architecture
• Two DDR4 UDIMM (288-pin) sockets
• Supports up to PC4-21300 (DDR4 2666)
• Supports 4 GB and 8 GB DDR4 UDIMMs
• Supports up to 4 GB on 32-bit systems
  NOTE: 32-bit systems cannot address a full 4.0 GB of memory.
• Supports up to 8 GB (unbuffered) on 64-bit computers
  NOTE: Maximum memory shown reflects the capability of the hardware and can be limited further in the operating system.

Are the expansion slots separate from the stated factory 4GB, so that whatever I can add is double what each slot can hold?