Hello xoxoMitsuxoxo,   This indicated a bad controller. The ECC errors are on the controller memory. There is not a DIMM to replace you need to replace the controller.   Good thing is you have the part number already:  Part number: TY8F9
Dell TY8F9 PERC 6GBPS 1GB Mini Mono RAID Controller w/ Battery 0TY8F9   The card, once installed, complains of ECC errors on boot, and on the off chance it does boot, disk activity stop, soft locking the os. I can't keep the system booted long enough to upgrade the firmware, any ideas?  
Dell TY8F9: Upgrading Firmware Issue