Question How to put 3 RAM Stick on ASRock B450M Pro4-F

[Thaipham3005]

I currently have my system (ASRock B450M Pro4-F, Ryzen 5 2600) with 2 RAM sticks (8GB/ 2666Hz each) running as dual channel on slot A2 & B2. Recently I need more RAM, so I decided to buy 1 more RAM stick, same type as the ould ones. But when I put all together, the system can detect 24GB, but only 8GB usable.

Any ideas how to get the the system to use all 24GB of available memory? I understand it cannot run as dual channel any more. If it only run as single channel, how the performance will effect?

 

[Phaaze88]

The performance loss depends on the application, and Ryzen is really sensitive to ram. The stick you bought probably wasn't compatible.
(There's an online Qualified Vendors List for your motherboard which displays ram kits tested and guaranteed to run.)

Not only do you have slower ram - at least 3000mhz is recommended - but you want to run it in single channel? That's too much. Guessing off the top of my head, and depending on the application... between 25 - 40% loss?
If you need more ram, return the stick you just bought, and get a 2x 16GB kit.