Pcie 3.0 vs Pcie 2.0 [ x16 ] Any Difference ? Tested in 11 Games

Pci express version 2.0 vs version 3.0 , Gen 2 vs Gen 3. Is there any real performance loss when a midrange/high end gpu used in pcie 2.0 slot ? 11 games bench-marked Test system details: pciex16 vs pciex4 Intel i5 8400 3.8GHz all core turbo clock speed Msi Z370 A-Pro motherboard gen 1, 2, 3 supported asus strix rx 580 8gb OC edition gpu hyper x predator 3200 mhz 2x8 gb , 3200 mhz duall Channel 2tb , 500 gb 7200 rpm ssd - samsung 960 evo, samsung 850 evo Dell u2515h (tested at 1920 * 1080 resolution) Windows 10 build - latest update Latest drivers used for AMD GPU/chipset while testing. vmreviews