Question RAM is slower than stock speed

Jul 25, 2019
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So I recently have just finished my build and I noticed on task manager that it says my memory is running at 2133mhz. I bought 4x8 Corsair Vengeance @ 3600mhz. My CPU is a 9700k and I have the Gigabyte z390 AORUS Pro Wifi. Also, I was thinking on updating my motherboard bios but I am not sure if I should. Any help/advice is greatly appreciated!