Mb orange light 2 time and 7 time

The blinking pattern of the LED lights on your Dell Optiplex 3046 MT — specifically, 2 orange blinks followed by 7 orange blinks — indicates a specific diagnostic code. Dell uses these blink codes to help identify hardware issues.

That sounds like a memory error.  Unplug the system and hold the power button for 30 sec.  Remove and reinstall the memory module(s).

Check again - if that doesn't solve the issue, try one module at a time in each socket until you isolate the bad module or bad socket.