Here is the sneaky thing they don't tell you about PCI Express slots.
The PCI Express bus is a port or slot that is commonplace in both the gaming world and custom PC industry. Without it, you won't be able to connect high speed and high data rate components to your PC, like graphics cards (GPU's) and NVME drives. So, the PCI Express bus is without a doubt one of the most vital features of any gaming motherboard, and has been commonplace in PC's for well over a decade now.
However, what is not very well known is that not all PCI Express cards are the same! PCI Express can connect your devices and hardware to function on one of two ways. Either PCI Express can connect your component directly to the CPU or it can connect it to the chipset, which is located between your CPU and some of your other components. These include your ethernet input jack or some USB ports, depending on the structure of your chosen motherboard.
This will raise some confusion over whether or not to invest in a motherboard that has dual PCI Express cards over a single slot. The common misconception is that two is better than one as you can slot in two graphics cards. However, usually, those dual slots only support lower-spec GPU's but doubled, as opposed to one large one such as the RTX 3080 from NVIDIA.
Take a look at the video below by YouTube channel, Tech Quicky, on The Sneaky Thing About PCI Express.