Optiplex GX620, no signal on monitor?

Where are the diognostic lights I see none I’ll check ram now 

Irishtechguy,

The amber light on the motherboard usually refers to a bad motherboard. It will need to be replaced. You can remove the memory and turn it on to see if you hear a no ram beep code. What are the diagnostic LEDS showing on the system?

if u could email me i would appreciate it 

Irishtechguy,

My apologies on my previous post.

The orange LED on the motherboard is the "flea" light. Meaning that the motherboard is getting power from the PSU.

Which chassis do you have? The DT or MT, is there is an added video card installed?  If one is installed, the monitor has to be connected to the added video card, not the onboard VGA out port.

Click the link below to download the Online Manual for location for the Diagnostic LEDs.

Dell OptiPlex GX620 Drivers, Downloads and Manuals

Yes it beeps when no ram but haven’t a clue what it mean 

What is that mt or md I have custom power supply it’s a Corsair cx430 

We need to know which chassis you have and if there is an added video card installed.

1. Open the User's Guide
2. Page 1 shows us that the Optiplex GX620 sold with four different chassis =
MT = Mini Tower Computer
DT = Desktop Computer
SFF = Small Form Factor Computer
USFF = Ultra Form Factor Computer

Now compare those pictures to your system.

USFF  

I fixed it but it isn’t booting up it says no recogniseable drive basically no software I put in a cd with software and nothing still same thing 

Advanced format drives require setting SATA to LEGACY EMULATION ATA or F6 Drivers.