AMD Flex Mode

[candycane]

I was wondering if I was using 3 sticks of RAM, would flex mode default to the dual channel RAM first and then go to the single channel RAM once all the capacity on the dual channel ones has been used up. I am using an AsRock x370 gaming k4 motherboard with a ryzen 7 3800x.

[BobVonBob]

I believe modern CPUs work like you said, dual channel until the dual channel memory is used up, single channel on the last stick. It's not ideal, and I'd honestly avoid it altogether if the sticks are different capacities, since I've had some weird hitching and crashes related to flex mode on mismatched sticks in the past. Granted this was a few years ago and on Intel instead of AMD.