Optiplex gx620 2 beeps on start up, displaying 123.

If windows 7 you need to burn a repair disc & run it. Go to Maintenance, creat repair disc (use one CD & mark it with Dell gx62 on top, repair disc run first on bottom)
Restart your computer and hold down escape, F1 or F2 to get into the settings in the CMOS. You must chang the boot order of your startup. In CMOS use arrows to right to Boot to change to CD ROM then HDD so your CD will go into repair before starting the HDD. Each CMOS is different but usually you can use the f5 or f6 to change the order and f10 to exit & save the setting. Restart your computer after you put the repair disc in & that should repair your start up.

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