Chipset Doesn't Seem To Support Pci-e Slots

According to this user manual, the Dell Optiplex 7010 small form factor has the Q77 chipset.
The computer also have two
pci-e x16 slots, but one is actually a pci-e x4, but it fits pci-e x16 (and caps the performance)
When I look at intel specs for the chipset, the chipset doesn't seem to support x16
https://ark.intel.com/content/www/us/en/ark/products/64027/intel-q77-express-chipset.html
I have a feeling that I am misunderstanding the Intel spec sheet. But, I want to get some clarification.

 

You are reading it right but it makes me wonder if there is a newer revision. I note that says, PCI2 Revision 2.0 also.

But if you look at the specs for this board, it clearly says PCIe x16 and Revision 3.0.

I might suggest you run Speccy (from the makers of CCleaner) and/or HWiNFO64 and see what they say you actually have.