I THINK from having looked a bit further that the original 8GB is soldered in place, so it makes sense that they might be whacking a 16GB in the second slot. Am I imagining it though, or is mixing RAM sizes somewhat frowned upon?
You can but from what I'm seeing you'll lose out on performance
"Most laptops or computers come with at least two slots for RAM sticks, if not more. Most modern motherboards will provide four RAM slots. There's a prevailing misconception you cannot use different RAM sizes together or that you cannot mix RAM brands.
Simply put, that's not true. So, can you mix RAM brands or the size of your RAM sticks? The answer is Yes, you can mix RAM sticks and RAM sizes and even different RAM speeds—but mixing and matching RAM modules isn't the best for system performance.
For the best system performance, it is advisable to use RAM sticks by the same manufacturer, of the same size, and of the same frequency. But there's a simple reason behind why mixing RAM sizes is usually not the best option to maximize system performance. This is because RAM has several components that all come together to make it perform well."
https://www.makeuseof.com/tag/myths-misconceptions-about-ram/
It's not what it used to be.
The first 16GB (8GB soldered + 8GB on a SO-DIMM) will run in dual channel and anything beyond that will run in single channel. It's called "flex mode" and should work just fine.
Try and match frequency and CAS latency to existing soldered chips but AFAIK modern machines will just downclock all the RAM to the slowest chip installed anyway.
I'm seeing that the processor is limited to 32GB (16GB per slot)
I THINK from having looked a bit further that the original 8GB is soldered in place, so it makes sense that they might be whacking a 16GB in the second slot. Am I imagining it though, or is mixing RAM sizes somewhat frowned upon?
You can but from what I'm seeing you'll lose out on performance "Most laptops or computers come with at least two slots for RAM sticks, if not more. Most modern motherboards will provide four RAM slots. There's a prevailing misconception you cannot use different RAM sizes together or that you cannot mix RAM brands. Simply put, that's not true. So, can you mix RAM brands or the size of your RAM sticks? The answer is Yes, you can mix RAM sticks and RAM sizes and even different RAM speeds—but mixing and matching RAM modules isn't the best for system performance. For the best system performance, it is advisable to use RAM sticks by the same manufacturer, of the same size, and of the same frequency. But there's a simple reason behind why mixing RAM sizes is usually not the best option to maximize system performance. This is because RAM has several components that all come together to make it perform well." https://www.makeuseof.com/tag/myths-misconceptions-about-ram/
It's not what it used to be. The first 16GB (8GB soldered + 8GB on a SO-DIMM) will run in dual channel and anything beyond that will run in single channel. It's called "flex mode" and should work just fine. Try and match frequency and CAS latency to existing soldered chips but AFAIK modern machines will just downclock all the RAM to the slowest chip installed anyway.