why put ram in slots 4 and 2

AMBIL SEKARANG

2000D RGB AIRFLOW Mini-ITX PC Case - Black - Corsair

UPDATE : Looks like putting both an AMD and an Intel branded module in the 3 & 4 slots works, I can even put only one module on the 3 or 4 slot, but anytime I put a module in the 1 or 2 slot, it refuses to work.

System shows 4 RAM Slots available, but only 2 are visible

In my task manager "Memory" tab under performance, It tells me that 4 RAM slots are available. But when I open the cover of my laptop, there are only 2 RAM slots visible.

MSI Z790 GAMING PLUS WIFI Motherboard, ATX ...

Customers have mixed experiences with the motherboard's slot capacity: while some appreciate the 4 RAM slots and 2 M.2 drive slots, others report issues with RAM slots not working and M.2 drives being defective.