Optiplex 620 will not start, 6 beeps

It is possible that the drive has failed, or the computers power supply has failed, or maybe the memory. Usually when a computer boots, you will hear a beep. if you hear more than the one beep, it will tell you what is causing the problem, let me know how many beeps you hear, if any.

it means your hard disk is not detected by system, check all connections of hard disk, if problem remains check with another working hard disk

Hello,
I would suggest that you reseat all the parts connected to the motherboard such as memory, PCI cards, etc.
Once you have reseated everything, try to boot it up. If you're still having the same error you might need to isolate the cause by removing everything from the motherboard then installing them one by one. after every installed part, try to boot up your system. It will give you a series of beeps. Please refer to the link below for the beep code

Dell Optiplex Beeps
You might also want to check some troubleshooting steps on that link to isolate the problem.
Regards

if the beep tones are 1 - 1 - 3 - 1 then you have a RAM error. It may be something as simple as a loose module. If all are properly seated and clamped in (you must look closely) then remove them one by one remembering which mod came from which slot. Each time you remove one try to start the PC If you remove one and it starts up then the one you removed is the bad module. You then need to have the module tested to see if it is good (the slot may be bad instead). You don't want to put a good RAM mod in a bad slot and take a chance of ruining it. You can however take the original and try putting it back in the slot to see if the computer will now read it.
To give you any further instruction I would need more information.
Hope this helps

DELL OPTIPLEX GX 620 PC WILL NOT START.
ONLY ORANGE LIGHT.

1.power supply
2.memory cards
at last mother board need changing !
hope it will help

replace with a new card. The beeps are indicitive 0f failed hardware 2 beep 2 beeps = video card series of 3 beeps keyboard ,malfunction etc etc so whichever card now gives you one long beep you had better start there.....

Hello , Ok this is alimentation problem because it gives low electric power to all your motherboard so try to change it :)

Open up the case and remove any add in cards and memory modules. Try to start up by adding these back one at a time until the unit stops booting normally. The light combination is not one recognised in the user manual so I am guessing you have a non-descript fault with one of your components. Be careful when you open the case as to not disturb the ribbon to the motherboard which controls the power, I have had a very long experience trying to get one of these reconnected!

Chuck,
The 6 beeps are an error code. You should note a pattern such as 3 beeps, short pause, 1 beep, short pause, 2 beeps. Also, you may have a set of 4 error indicators on the back of the unit that will show a pattern of green and yellow lights. In any case, you will want to try to run the Dell diagnostics. Let us know the beep pattern and the light pattern and we should be able to give you some more specific information.
R-