Question One ram stick is 2133mhz 8gb and the other is 0mhz 2gb?

[Adam..1]

When my game started lagging last night I had a look and it says that one of my ram sticks is running at 2133mhz when it should be 3200mhz. And the other ram stick says it is 0mhz and only 2gb? Just a casual gamer so bios confuses me but not sure why it suddenly bugged out like this. For reference I have a Gigabyte A520M MOBO and Corsair Vengeance 16gb ram.

 

[Aeacus]

Based on description, one of your RAM sticks died on you and system reverted to default JEDEC speeds, hence why another stick is running at 2133 Mhz.

Now, you have several options:

1. Power user level - Do more troubleshooting, by running memtest86, to confirm it for sure.
2. Standard user level - Buy new RAM set, replace it by yourself and RMA the old set (if it has warranty left).
3. Casual user level - Haul your PC to PC repair shop and pay them for diagnostics and repair.

but not sure why it suddenly bugged out like this.

Hardware dies on daily basis, often without any apparent reason. That's why hardware comes with warranty. If hardware never dies, there wouldn't be a need for warranty at all.