How does the number of pins in a pci-e connector affect the operation of video cards in crossfire?

Question

Video cards

On my motherboard (ASUS P8H77-V) there are 2 Pci-e x16 connectors, and the second connector actually has only half the pins, the right side of the slot is just for show. In programs like hwinfo, this connector is designated as Video Bus: PCIe v2.0 x16 (5.0 Gb/s) @ x4 (5.0 Gb/s).
I heard that only the video memory of the 1st video card is used in crossfire, if this is the case, then what I described above does not affect the speed in games. However, this is just my guess, I want to know your opinion.

Answer 1

When building a crossfire , only one card's memory is available . Both are used, but the information in them is duplicated. An old problem with multiGPU configs.
Second slot: even if you have contacts in the slot physically - this slot is connected to the south bridge via PCI-E 2.0 x4. For those GPUs from which it makes sense to fence multigpu, and not more meaningful to take a card at a higher level and not suffer from the lack of multigpu support in games - this is a bottleneck. The main PCI-E x16 slot gives a bandwidth 4-8 times higher (depending on the inserted CPU socket - the slot is connected directly to the CPU and it determines the bus version). What do you think happens with such a bandwidth imbalance? CF is implemented just for show.
But a great thing for sticking in some kind of PCI-E x4 or x8 raid controller, or something else that doesn’t have enough x1 slot.
I can't tell you about miners.