Question System won't boot - lights 1 & 3

[Maximuzzm]

Dell optiplex 790 mt won't boot has been crashing randomly for weeks now... Now it won't boot even to bios... Lights one and three... Supposed ram problem but I took all ram out but one still doesn't boot light one and three.. is this battery for my Mobo going out or what

 

[Maximuzzm]

Took all ram out now I'm getting light one with beeps

 

[Maximuzzm]

Put a different ram stick in still lights one and three

 

[Maximuzzm]

I took x2 sticks of ram out... seems to be working now but i only have 8 gigs of ram now... this always happens no matter what ram I use... It was working fine for like a year.. had the same problem like a year ago... idk why it keeps giving me ram error