No, you cannot use a PCIe 2.0 slot to install this processor.
You must purchase/acquire a motherboard that has the PROPER socket and bios support for this processor.
Here are some motherboards that will support your processor:
http://processormatch.intel.com/MotherBoards/CompatibleBoards?componentName=i7-7700K Compatible Motherboards
Your question indicates that you may want to acquire the support of a good computer support shop.