I am going to purchase an 8GB 1333MHz DDR3 RAM stick for desktop computers, my computer supports dual channel, I will post my RAM specifications below, and I have observed a strange and interesting phenomenon: different programs(and different sections of one program) report different RAM frequencies...I assume my RAM is 1333MHz:
Will I get 12GB 1333Mhz DDR3 working primary memory in total or there will be problems?
From your other question we already know that your specs are Intel J1900 on ASRock Q1900M.
Your CPU officially supports up to 8 GB of RAM, but some people have reported success with 16 GB setups and specs of your motherboard claim 16 GB will work (many J1900 boards do). So capacity-wise it shouldn't be a problem. You won't benefit from dual channel with mismatched sticks though.
Your current RAM stick is capable of working at 1600 MHz, but the CPU is limited to 1333 MHz, therefore RAM is underclocked. With that CPU it probably doesn't matter much.
Your motherboard is using DDR3 memory in laptop form factor (SODIMM). Your current memory module is DDR3 (not DDR3L) and so should be the other one.
It's a tough choice between additional 4 GB module for 8 GB total in dual channel or 8 GB module for 12 GB in single channel. If you're using this PC for memory-intensive work (VMs, IDEs...) I'd go for 12 GB. It will be slightly slower, but not as slow as paging to disk when the memory is full.
