RAID 5 issue

I have a system with 3 Sata disks of 250 GB configured as RAID 5. Some time ago I got the message RAID degraded, and one of the disks was in error status. I replaced the disk by a new one, the RAID rebuilded itself, and the problem was solved. 3 weeks later, same problem again, and even the same disk. Again I replaced the disk with a new one, same scenario, rebuilding, and ok. But now the problem came back after only one day, so I don't believe Samsung makes disks that bad I was thinking that the mainboard is the troublemaker, but if the SATA port is defective, he doesn't recognize the disk. I don't format the disk before I install it in the RAID, I just connect it, and the RAID starts to rebuild, am I doing something wrong ?

At least in my experience your not doing anything wrong. But maybe your RAID controller is going bad.