One of the PCI slots of my Dimension 8300 seems bad. (The 3rd one from the bottom, or the one 2 below the AGP slot.)
When I put multiple types of multiple SATA cards in the 'bad' slot, many hard drives (even new ones) which pass drive diagnostics get file corruption after a few days. Even after formatting.
I did try un-/re-installing the cards' drivers. The cards are http://www.siig.com/it-products/controllers-storage/serialata/pci/esata-ii-150-pci.html and http://www.siig.com/it-products/controllers-storage/serialata/pci/serial-ata-4-channel-pci.html
Next I tried putting my Ethernet card, http://www.dlink.com/us/en/home-solutions/connect/adapters/dge-530t-dge-530t-32-bit-10-100-1000-base-t-pci-adapter , in the 'bad' slot; it isn't even recognized (doesn't show up in WinXP Pro sp3 Device Manager) there.
The slot looks fine. RAM and hard drive and CPU diagnostics all pass; and the cards all work perfectly on the other slots.
Any suggestions other than "don't use the slot", please?