RAM upgrade for desktop pavilion 590 i7

[Sarahmw333]

My desktop is able to take up to 32 gb of RAM since I have a 64 bit OS (2 RAM Modules) . My question is regarding upgrading the RAM because it only came with 12gb. The product description on HP's website says it takes DDR4 PC4-21300 (DDR4 2666) UDIMM RAM. So I know that I need to buy unregistered 288-pin RAM with sea above specs but I'm wondering is generic RAM is compatible or if I need to buy a specific kind or if I'm missing any of the required specs for this desktop as to the type or brand of RAM I should buy. There are so many out there and the 16GB is rather expensive so I want to make sure that it's going to work in the computer before I buy it and would greatly appreciate any assistance or advice on this. 

[skywalker2077]

Please explain how it came with only 12GB of RAM. The product spec gives the link to the motherboard spec.

https://support.hp.com/us-en/document/c05991291

It has only 2 memory slots. Are both the slots occupied? Guess not.

What is the current RAM  brand on your PC? Is it Kingston HyperX Fury? Also, note the part# on the RAM.

Any brand of PC4-21300 (DDR4 2666) with either 4GB/8GB (for 32 bit OS)  or 16GB (for 64 bit OS)  memory will support. To get the best performance, it is recommended to buy the same exact brand.

Guess, in your case, you have 1 x 16GB RAM and you need another one with same spec & brand for making it 32GB.

[Sarahmw333]

Thank you for your reply. I bought the PC refurbished and haven't actually even had time to look at how the memory is set up inside, but I’m assuming there's an 8gb card and a 4gb card. I want to ultimately get 2 16gb cards and from what I've read I'm definitely going to buy them at the same time as part of the same package/order to make sure they "play nice together". I followed the link to Crucial's website and found exactly what RAM I need to buy so thank you to whomever posted that link on here as well! Again, I appreciate your assistance and input!