WRONG ....YOU WILL LOSE performance running it in the second slot , it is only X4.
1 x PCI Express x16 slot, running at x4 (PCIEX4)
It states it on the specs page:
1 x PCI Express x16 slot, running at x16 (PCIEX16)
* For optimum performance, if only one PCI Express graphics card is to be installed, be sure to install it in the PCIEX16 slot.