PCIe RAID 1: CPU slot + Chipset slot or 2x Chipset slots?

I have read here that it is best to put one of the drives on the CPU slot and the other drive on the chipset slot to improve performance

I know there is a pci express extension wich allows 2 m2 on a The most common M-keyed M2 slot usually have up to 4 lane PCIe, so

pcie 20 x16 slot An M2 PCIe SSD solid state drive storage slot on a motherboard, ssd in motherboard slot ssd in motherboard slot Stock Photo Hard disk SSD m2 on

pcie slot for gpu 2 interface connected data through either SATA, USB, and now PCIe lanes as opposed to the more common SATA connection to connect your HDDs and SSDs to the