Pcie 3.0 on pcie 1.0

you could have combined threads...

PCI Express 3.0

PCI Express 3.0 Base specification revision 3.0 was made available in November 2010, after multiple delays. In August 2007, PCI-SIG announced that PCI Express 3.0 would carry a bit rate of 8 gigatransfers per second, and that it would be backwards compatible with existing PCIe implementations.

definitely performance reduction because of the bandwidth limitations of the PCI 1.0 slot..

might not be compatible with your motherboard and it's PCI 1.0 slot.
remember PCI 2.1 has issues with older 1.0 slots and a BIOS update didn't always do it...
it said that PCI 3.1 is backwards compatible but I do not see where it says PCI 1.0.
50-50 chance..