Pc Dell optiplex330 Tower mini

Hi

""I just replaced my old motherboard with a new one. Indicator lights 1, 2, and 3 are green. Light 4 is off. Can anyone help?""

That is a failure during POST I believe.

Possibly Memory/RAM error,   REMOVE and Re-seat.

If in doubt please ask.

Saya rasa itu adalah kegagalan selama POST.

Kemungkinan kesalahan Memori/RAM, LEPASKAN dan pasang kembali.

Jika ragu, silakan bertanya.

AND USE GOOGLE TRANSLATE.

Saya coba beberapa kali cabang dan pasang  memori , tetap juga lampu 1,2,3 nyala hijau. Lamp indiktor 4 mati

I tried installing the memory modules in various slots several times, but the lights for slots 1, 2, and 3 still show green. The indicator light for slot 4 is off.

Hi

Sorry, but you may need to take it to a Dell repairer. 

for old motherboard replacement, OP should still try replace cmos battery with a new battery and follow by clear cmos using motherboard RSTRCT jumper.