Assuming everything worked fine before you rebuilt it then somewhere along the line something changed. Did you rebuild it in the original case? Have you tried to reset the BIOS to default values? The 3010 is showing some age  now, have you tried to replace the CMOS battery with a brand new battery that is one newly purchased? What other new components did you add or upgrade?
I have a dell optiplex 3010 MT, BIOS = A12 . The issue is is that when i dismantled this computer and rebuilt it it comes up with 4 messages. Previous fan failure, then the exaust fan is spinning but the computer thinks its broken and doesnt spin. And it says hard drive not found. I have tried 12 HDDS and 2 SSDS with No OS and they had an OS. I have swapped out sata power cables and sata data cables but still no luck. Please help.
My Computer Wont Detect any of my hdds or ssds