1. How To add the R520 PCI X Riser card In the option box there is a PCI X riser card Unplug the riser card from the Altos R520 Pull the plastic hook like it is shown in like the one shown here and identify the Full Height Riser card the picture F Shift the card like in the picture to unlock Plug the new PCI X card and shift it to lock The riser card is ready to be installed and remove the card All the How To guides can be found on http support acer euro com documents howto SO R51PC 101 R520 PCI X Full Height Riser 1x PCI X 133MHz slot 46 R51PC I01