andylb said:

AcykenRox said:

I have Acer Nitro 5 an515-53-52fa with GTX 1050, 8gb ram, my question is can I add a 16gb ram? Or should I add another 8gb ram?

You can add another 8gb to make 2 x 8gb or 1 x 16gb and leave one slot empty. RAM operates on Dual Channel only on the matched portion so equal RAM is the excepted norm. Your existing 8gb stick is 2666mhz so buy a 2666mhz. Max RAM for your model is 2 x 16gb for 32gb total.
Link below is to Crucial who guarantee compatibility for your exact model, I write down the part number and buy from Amazon, it's cheaper and faster delivery
Please click YES if I have answered your question, thankyou

https://www.crucial.com/usa/en/compatible-upgrade-for/Acer/nitro-5-an515-53#MEMORYFilters

Hmmm.  So you're saying 8 GB + 8 GB is better than 8 GB + 16 GB??   Really?  That's absurd.

And you're also saying that having a single stick of 16 GB and keeping one slot empty is better than 8 GB + 16 GB??  Really?  That's also absurd.
Are the Acer moderators telling you that?  Where are you getting your information? 

andylb said:

The official Acer provided ram placement chart
This chart is provided by Acer and informs the user the RAM configuration Acer officially supports. I am sure that you can use oddly matching RAM but I try to keep my answers within the Official Acer specs

Ok, now I understand your confusion.  The service guides have a target audience of Acer Technicians or computer technicians.  They are primarily for Acer OEM equipment.  
An Acer engineer and technical writer created a chart based on the combinations they know they will be shipping.
Every Acer Technician knows that the mainboard supports unequal sizes so they know that chart is not set in stone for consumer DIY upgrades.  Also, as was stated in a different thread, Acer ships some PCs with unequal ram sizes.  I bought an Acer computer in 2014 that had unequal sized ram.  You can check userbenchmark if you are unsure if it supports.

I'll give you another example of why you have to be careful with the service guides.
There's hundreds of posts on this forum that say the max SSD size for some different Acer model is 256GB.  This simply isn't true.  When Acer lists 256GB in the service guide for a certain model, they are simply saying that is the size that they tested.  They had no reason to test a greater capacity because they had no intention of shipping that model with a greater capacity.  Again, the service guides are primarily about Acer OEM equipment.  They don't test the consumer DIY stuff.   They don't really need to test it because Acer doesn't use a BIOS whitelist like some other companies do (did).   Which is why I like Acer.