Q Should I get a motherboard with two PCIe x16 slots or more x1

I installed the adapter in the last full size PCIE slot and it works fine When installed in the x1 slot it does

Dell XPS 8700 comes with a one PCIe x4 slot on the systemboard You can refer to picture below for it

x16 slot However, there is usually a cost increase incurred with higher lane counts PCIe Slot Differences Photo from 20050531pci-express-cards

x1 slot PCIe x1 slots replace the standard PCI port and are about 1 inch long They move data on and off the motherboard at up to 250 MBps in