Most of Dell's Perc controllers are from LSI Logic. Perc3 are Ultra160 SCSI RAID PCI controller (160MB/s), Perc4 are Ultra320 SCSI RAID PCI-X controller (320MB/s), and Perc4e are Ultra320 SCSI RAID using PCI-Express. You will usually see SC, DC, QC, Si, Di, etc associated with the Perc Controllers which specify how many channels the card have (eg. Perc3/DC is Dual channel Ultra160). You can get most of the cards at WWW.SCSI4ME.COM for a much cheaper price than directly from Dell.