I have MSI 890FXA-GD70, in the specifications I read that it supports 32 GBs. It has 4 slots, so 8 GBs each. Can I install 3 slots and not 4? the specifications said it's dual channel, is it like Intel dual channel? where you get better performance installing 2 or 4 slots as opposite to 3???
Yes u can, but it will be running in the flex mode, which is fine.
As far as performance goes, 2 or 4 slots vs 3, it would be barely measurable and not noticeable in the real world.