Optiplex 760 Making Beeping Noise

Hi Aiden12345,

The 3 & 4 LEDs being lit indicate a memory issue, specifically "Memory modules are detected, but a memory power failure has occurred."

I would suggest disconnecting then reconnecting the memory modules to see if that helps. Instructions can be found here:

https://downloads.dell.com/manuals/all-products/esuprt_desktop/esuprt_optiplex_desktop/optiplex-760_service%20manual_en-us.pdf

Let us know how you get on, thanks.

Solid Amber power button is Bad CPU/Motherboard

Blinking Amber is Bad power supply.

https://www.dell.com/support/article/us/en/04/sln284978/

Power LEDs

      Off         Blinking Amber  Solid Amber  Solid Green  Blinking Green

The computer does not appear to get power from the Power Source.	The PSU is receiving power from the Source, but is unable to distribute it.	The PSU is working, but the system doesn't process data.	The system processes data and has begun POST tests. (See the diagnostic LEDs at this point)	The system is in a hibernate or sleep state.

 

Diagnostics LEDs

LED Pattern(1 2 3 4) LEDPattern StateName StateDescription Suggested Resolution

	Off	Off	System POST complete — LED time-out has occurred	If the LEDs came on and then went off, look at troubleshooting the display and the operating system. If the LEDs never came on at any point then look into a power issue.
	4	RCM	BIOS checksum failure — Recovery mode	Reset the BIOS and clear the NVRAM If this occurred after windows updates, check your startup wsn't corrupted.
	3	CPU	CPU configuration activity or failure; CPU Cache failure	Disconnect all external peripherals and configure PC down to PSU, Motherboard and CPU If fault continues contact your technical support If fault stops, plug disconnected parts back one at a time until fault re-occurs. Contact your technical support to take this further.
	34	MEM	Memory subsystem configuration activity or failure	Remove all memory from PC, does the LED code change? If it doesn't contact your technical support If it does add the memory modules back one at a time until the fault re-occurs, test that module in another slot and contact your technical support
	2	PCI	PCI device configuration or failure	Remove all external peripherals and all internal PCI devices If fault continues contact your technical support If fault stops, add parts back one at a time until fault re-occurs and contact your technical support
	2 4	VID	Video subsystem configuration or failure	Ensure the video cable is connected to the correct port Reseat any add in graphics cards If fault continues, remove any add in graphics cards and test with known good monitor and video cable Contact your technical support once you know which part the fault follows
	23	STO	Storage device configuration or failure	Reseat the cables from the HDDs to the motherboard If fault continues try substituting a known good HDD into the system and contact your technical support
	234	USB	USB subsystem configuration activity or failure	Remove all external peripherals and any internal CRUs If LEDs change, add parts back one at a time until fault re-occurs and contact your technical support If fault remains the same with parts removed, contact your technical support
	1		No memory detected	Reseat all memory modules If fault continues, try the memory in different slots and contact your technical support
	1 4	MBF	Fatal system board failure detected	Contact your technical support
	1 3		Memory is detected, configuration or compatibility error	Reset the BIOS and clear the NVRAM and any previous errors Remove all memory from PC, (This includes any Graphics cards.) does the LED code change? If it doesn't contact your technical support If it does add the parts back one at a time until the fault re-occurs, test that part in another slot and contact your technical support
	1 34	PRV	Indicates system activity preceding video initialization	Remove all external peripherals and any internal CRUs If LEDs change, add parts back one at a time until fault re-occurs and contact your technical support If fault remains the same with parts removed, contact your technical support
	12	CFG	System resource configuration	Reset the BIOS and clear the NVRAM and any previous errors Remove all external peripherals If LEDs change, add parts back one at a time until fault re-occurs and contact your technical support If fault remains the same with parts removed, contact your technical support
	12 4		Reserved	Reserved
	123	POV	POST complete — Onscreen error message	Troubleshoot as per the error message onscreen
	1234	STD	POST complete — OS hand-off complete	The Power On Self Test has passed all checks Troubleshoot the HDD and the Operating System