My system has a 5oogb Seagate sata installed internally and an Antec hard drive esata caddy which has 500gb sata's swapped around. When I attempt to install a second internal sata, the system will not boot. The original configuration had three internal sata's, but apparently two of those failed simultaneously and I have since been unable to add internal sata's. Both the failed sata's were confirmed as having failed by the manufacturer. I am running Ubuntu and the system operates normally until I try to add internal storage. A motherboard failure seems a logical explanation for my problems but I don't know how to isolate or identify the problem. Should I live with the situation or replace the dh55hc?