I am surprised that you can get a X5690 to work on that Version 1 motherboard, but that is good news if it holds up to be stable. That remains an expensive processor, but your discovery opens the potential to use other less expensive ones that "should not work".
The BIOS may have been downsized from the Z600.... perhaps that is why you see hints of 2 processors. Likewise for the memory/chipset entries in the BIOS temp/rpm section. I added on a chipset fan to my V2 6-mem-slots Z400 as shown in an earlier post and its RPMs show up under the Memory section if I recall correctly.
The PCI entry is for that bottom front motherboard fan header.... it is to pull into the case cooler ambient air and blow it across the PCI cards down in that area to the rear. Hence the name....
I'll get you some added info on my BIOS temp/rpm readout later.