PCI-E x4 slot with 164 pins?

My Motherboard is an old Gigabyte GA-P67A-D3-B3. It has two 164 pin PCI-E slots. One is marked x16 and the other is marked x4. Why does a 4 lane slot have 164 pins? I had thought the difference between the slots at x1 x4 x8 x16 was the numbers per lane, making larger headers the more lanes you increase to

So am I not going to be able to plug my PCI-E x8 peripheral into the x4 slot (with 164 pins)?

I think you can plug your PCIe x8 peripheral into the slot but it will operate at PCIe x4 speeds and even slower if you plug something into the PCIeX1_1 or _2 slots. As per:
Thank-you for your reply, I do appreciate your time :). I guess I should have said I have read that page referring to: "1 x PCI Express x16 slot, running at x4 (PCIEX4)". I guess a better question would have been, how would an expansion slot of 16 lanes only operate at 4 lanes?

Thank-you again for your information.
{I did not mean to quote, I was not aware the reply button in your comment would be a quote unlike other message boards I have used, could not find a way to cancel}


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Oh the answer to your question is that the PCIe slot technology is flexible like that. Fun Fact: You could take a PCIe x1 device and put it in ANY PCIE slot..even a PCIE x16 slot and it would work. Knowing that a motherboard manufacturer can use a large x16 connector but tell the user it operates at x4 speed.

As I understand this technology the limitations of all these speeds is dependant on the chipset. The more expensive chipset/boards support more PCIe lanes. I believe the PCIe x1 runs at 250MB per second which is pretty fast all by itself.