Optiplex 5040 SFF DDR3L memory population question

Question

Hi,

I've an used Optiplex 5040 SFF which was sold with 1x 8 GB SK Hynix HMT41GU6BFR8A (2Rx8 PC3L - 12800U - 11 - 13 - B1).
As the unit supports up to 16 GB of RAM (4x 4 GB or 2x 8 GB) I've decided to buy another used pair similar to what I've already installed.
So I got a HMT41GU6DFR8A (difference is only fifth character from the right - D instead of a B) which has the same specs printed on (2Rx8 PC3L - 12800U - 11 - 13 - B1).
After reading some manuals and community posts in regard of dual channel both memory modules should be placed in slots with white levers marked with numbers 1 and 2.

The slots are like this:

3 black \
channel A
1 white /
4 black \
channel B
2 white /

Unfortunately the system won't boot, not even the BIOS/UEFI - the power LED flashes amber and that's it. No beep code, nothing.
After trying different slot populations I figured out the only working one would be 3 and 1 - and then only single channel.
According to CPU-Z both modules run with exactly the same speed, timings, voltage.

I've also removed the CPU and installed it again as well as cleaned the memory modules and slots - so it shouldn't be any contact issue.

Next try was to get a supported 16 GB kit so I went over to the Crucial website, filled in Dell Optiplex 5040 and ordered a suggested pair of memory - unfortunately one of the two modules was DOA.

Trying to mix memory also only works in slots 3 and 1.

Question: why does populating anything different than 3 and 1 not work? I mean even if it would be only single channel at least it should work by using 1 and 2?

Any suggestion regarding memory which definitely works in this computer?

Thanks in advance.

Dorian J. · Accepted Answer

After replacing the motherboard with an identical used one I was able to use both other memory slots too There was a pin missing within the CPU socket of the old motherboard.

DELL-Cares · Answer

Hi,I see you’re looking for technical assistance. If you require our help, you could initiate a private/direct message with us, and we’d be glad to assist you.

redxps630 · Answer

Curious whether your pc would post if you install only one ram in DIMM 2 or 4?

Dorian J. · Answer

Unfortunately not. A single memory module only works in 3 or 1 - not in 4 or 2. Seems the whole right channel (4 and 2) is not usable at all somehow.

The power LED will start to flash amber as soon as a memory module in either 4 or 2 or both or a combination of 3,1 and 4 or 2.

redxps630 · Answer

Seems slot 2/4 are disabled or broken. Have you run system diagnostic test?

try clear CMOs settings

Disconnect the system from external power source
Remove the computer cover and locate the CMOS coin cell battery
Remove or disconnect the coin cell battery.
Press the power button for at least 10 seconds to drain all residual power from the system.
Re-insert or re-connect the coin cell battery.
When the system is powered on, it will warn that the date and time is not set, indicating a successful reset.

well at least you still have two left and 16Gb is plenty of ram.

Dorian J. · Answer

System diagnostics didn't find any errors - only HDD because I've unplugged every drive so that's supposed to fail then.

CMOS clear was also done already and didn't fix anything.

True, at least two slots are still working so I can use the maximum supported amount of memory - just not in a dual channel setup.

Not quite sure if it's the board itself or the CPU so I try to test replacements as soon as I get cheap ones.

Thanks so far for your help

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Optiplex 5040 SFF DDR3L memory population question

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