Question New RAM stick not recognized, but frequency changed

Feb 24, 2022
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I 've been running on 8gb DDR4 single channel for more or less 5 years, yesterday I bought a second 8gb stick (Both are HyperX Fury) and I just installed it.
On my first attempt, the pc wouldn't show image, so i changed them to the other channel. Now the pc turned on, and in task manager I see the RAM frequency changed from 1200 to 2666mhz, however my sistem still says i've 8GB of ram, using one slot.

Why did the amount of ram available not changed, but the frequency did?

FYI, before installing the ram I updated to the last bios uefi (Asus prime B350-plus/Ryzen 5 1600/RX 570 8GB)