solid yellow light on dell optiplex520

May 12, 2011 at 06:48:48
Specs: Windows XP
dell optiplex 520 shows a solid yellow light and has a error light codes in 1&3

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May 12, 2011 at 07:32:17
Solid yellow light:
The Dell Diagnostics is running a
test, or a device on the system
board may be faulty or incorrectly

Error light codes:
Memory modules are
detected, but a memory
configuration or
compatibility error exists.

Hope this helps

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May 12, 2011 at 08:19:27
There is no Optiplex 520 model.

It's GX520, or DGX5xx, or X 5xx, or XL 5xx, or XMT 5xx

Go here for how to find the Service tag "number":

Tell us what it is.

Dell usually has very good documentation about their models.

Assuming it's an Optiplex GX520.....

Dell™ OptiPlex™ GX520

HTML version
Dell™ OptiPlex™ GX520 User's Guide

Choose a system / case type


Dell™ OptiPlex™ GX520 User's Guide
Desktop Computer
(regular width tower case - the optical {CD or DVD] drive is mounted horizontally across the case width)

Troubleshooting Tools and Utilities

System Lights

Power Light (Power led)

Solid yellow

Problem Description

The Dell Diagnostics is running a test, or a device on the system board may be faulty or incorrectly installed.

Suggested Resolution

If the Dell Diagnostics is running, allow the testing to complete.

If the computer does not boot, contact Dell for technical assistance.

Also see Diagnostic lights (Diagnostic leds)


If you HAVE NOT changed which ram modules you have installed, or in any case....

See response 2 in this - try cleaning the contacts on the ram modules, and making sure the modules are properly seated:

If you HAVE changed which ram modules you have installed .....

Ram that works in another mboard , or any ram you buy or have lying around, may not work properly, or sometimes, not at all - even if it physically fits and is the right overall type (e.g. SDram, DDR, DDR2, etc.; PCxxxx, xxx mhz) for your mboard. In the worst cases of incompatibilty your mboard WILL NOT BOOT all the way with it installed, and the mboard may not even beep - the ram has to be compatible with the mboard's main chipset, or in the case of recent mboards, compatible with the memory controller built into the cpu.

If you still have the ram that was installed when the system worked fine, and you know which ones they were, try installing just that ram.

If you're not sure which modules were installed when the system worked fine, install one module at a time and see whether your system will then work normally.
Then try installing all the modules that allow the system to work normally when installed by itself, and see whether your system will then work normally.

See response 5 in this for some info about ram compatibilty, and some places where you can find out what will work in your mboard for sure:
Correction to that:

Once you know which module ID strings (part numbers) work in your mboard, you can get them from anywhere you like that has ram with those ID strings.

If you have brand name ram, it is usually easy to look up whether it's ID string (part number) is in a list of compatible modules found by using your mboard or brand name system model number.
If the ram is generic, that may be difficult or impossible.

Some ram manufacturer's modules do not strictly adhere to the JEDEC standards that most mboards bioses use to determine ram settings.
In that case, the ram settings in the bios Setup that the bios has automatically chosen may not be correct.
Check the ram settings in your bios - the ram voltage, and the ram timing numbers - those should be the same as for the specs for the modules themselves. Often the ram voltage and timing numbers are printed on the label on the modules.

If the voltage setting or timings settings in the bios are different from the specs for the ram, change them in the bios. The timing numbers must be as close as you can get to the same, or slower timings (higher numbers = slower) - you won't notice the difference the slower settings make.

If you have a mix of different modules
- don't mix ram that different voltages are specified for - the bios will force the ram to use the lowest voltage, if "by spd" or similar is used (default settings) - ram that a higher voltage is specified for is more likely to not work properly in that situation.
- the bios settings must be those for the slowest timing settings of all the modules, or slower (higher numbers = slower).

You MAY be able to custom set the ram voltage to the higher ram voltage in the bios if you do NOT have the bios set to detect the ram "by SPD" or similar, however, you must NOT exceed the max voltage range for the modules that require a lower voltage, and that can be hard to determine, unless you can find detailed specs - e.g. if the ram is Kingston ram that doesn't have a brand name system specific part number, that info is easily found.

If your ram passes a ram test, it's working fine, even if you can't determine whether it's listed for your mboard or system model anywhere

If you do a ram test, do that AFTER having tried cleaning the contacts and making sure the ram is seated properly - otherwise any errors found may be FALSE.
If the ram is incompatible with the chipset, or on more recent computers, incompatible with the memory controller built into the cpu, it will likely FAIL a ram test - that is NOT a true indication of the ram being faulty - there is probably nothing wrong with it, and it will pass the test if installed in a mboard it is compatible with.


If you want to try a memory diagnostic utility that takes a lot less time to run a full pass than memtest86 does, this one is pretty good - Microsoft's
Windows Memory Diagnostic:
Windows Memory Diagnostic is limited to testing only the first 4 gigabytes (GB) of RAM.
It can be toggled (press T) to do a standard or a more comprehensive set of tests - use the default 6 test one first - if it passes one pass of that, use the latter one. A few of the tests in the latter set are intentionally slower.
If you don't have a floppy drive, see the Quick Start Information at that Microsoft link for how to make a bootable CD of the Windows Memory Diagnostic (you need Windiag.iso - you don't necessarily need to use the program they mention to add it to the CD).

If you have 4gb total or more ram installed, use Memtest86 to test the ram.

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