I use Crucial memory and when somebody brought me a computer I go to the Crucial site, run their software to determine what that specific computer will use.

Cost is same as most places but I've been content with their results.  I currently am upgrading a friends laptop and it has 8GB of ram but won't accept any more.  However I am upgrading the drive to an SSD which should make a difference.

https://www.crucial.com/

https://www.crucial.com/upgrades  you download the Crucial scanner and run it.  I've checked it with Malwarebytes and AVG as well as Microsoft Defender and never found any virus, and firewall doesn't report any traffic from it.