XPS 8960, troubles installing 64 GB ram

Question

When I bought it last year my XPS 8960 desktop came with 2x8GB memory installed. To give it a performance boost, I recently bought a 2x32 GB memory kit (Kingston KF556C36BBEK2-64) to upgrade it to 64 GB. According to Dell specs the motherboard supports up to 64 GB, but unfortunately when I insert both 32 GB DIMMs then the system won't start and generates system diagnostic light code 2,4. (see Service Manual, page 85). When I insert one 32GB DIMM and one 8GB DIMM then all is ok, and the system starts and detects 40GB as expected. Same when I swap 32GB DIMMs and swap location for 32GB/8GB. So both 32 GB DIMMs seem ok, but only the combination of two 32GB DIMMs inserted at the same time does not seem to work. Is this a BIOS bug? Does anybody else have experience with upgrading to 64 GB DDR5 memory?

Best regards, Robert H

anne_droid · Answer

Hi

If each stick works alone in both slots but not together, it is likely a compatibility/timing issue with that specific kit rather than a bad module or slot.

Update the system BIOS to the latest XPS 8960 revision first; at least one important BIOS release for this model is marked as “crucial”.

After updating, clear NVRAM and reset BIOS to defaults so the memory configuration is re‑detected cleanly.

On XPS desktops there is normally no user‑exposed XMP; the RAM should run at JEDEC speed (often 4800 or 5200 MT/s), even if the kit is sold as 5600+.

That is expected and not an error as long as the system is stable.

Element115s4 · Answer

When I look at approved 8960 memory @ Kingston, I see this one: KCP556UD8-32. How did you select that module kit?

AllOtherNicksAreOccupied · Answer

@anne_droid​ Thanks! I will try this and report back...

AllOtherNicksAreOccupied · Answer

@Element115s4​ Hmmm, I wasn't aware there is an approved memory list - where did you find that?

DELL-ChrisM2 · Answer

@AllOtherNicksAreOccupied​ * Go to the top of the XPS Desktops board* Open, FAQ XPS Desktops* Open, FAQ XPS 8960

Element115s4 · Answer

@AllOtherNicksAreOccupied​  Yes, along with the list Dell provides, Crucial and Micron along with Kingston actually have system specific memory guaranteed to work. I was happy to get my XPS 8950 64GB of memory before it tripled in price! I think Crucial might be getting out of the game soon, IIRC.

AllOtherNicksAreOccupied · Answer

@DELL-ChrisM2​ Thanks! As I mentioned, I was not aware of such a list. I just used the Setup and Specifications manual for the XPS 8960, page 18, for retrieving the requirements for new memory modules. Assuming that adhering to those specs would be enough. But apparently there is more, because my 64 GB config with Kingston KF556C36BBEK2-64 still isn't working for both slots. 😬

AllOtherNicksAreOccupied · Answer

@Element115s4​ No. I bought Kingston KF556C36BBEK2-64 - wasn't aware of list and assumed my kit would work also as it meets the requirements mentioned in Setup and Specifications manual.

AllOtherNicksAreOccupied · Answer

@AllOtherNicksAreOccupied​ I tried resetting BIOS to defaults and removing CMOS battery, but that didn't help. Still the same results. The BIOS will detect 8GB+32GB, independent of which module is in which slot. But not detect 32GB+32GB; it will again generate system diagnostic light code 2,4 if I insert both large DIMMs.  Any other suggestions?

Element115s4 · Answer

@AllOtherNicksAreOccupied​  Yes, the specs are not going to be enough to make sure memory will work with Dell PCs. Only use approved memory or it will be a gamble. Just check any memory makers website and find the system specific tool/area and enter your Dell model. Bad timing now because memory pricing is through the roof. :O

alanduken · Answer

@anne_droid​ If each RAM stick works alone but not together, it’s likely a compatibility or timing issue with the kit. Update the BIOS to the latest version, clear NVRAM, and reset BIOS to defaults so memory is detected properly. On XPS desktops, RAM runs at JEDEC speed even if rated higher, which is normal as long as the system is stable.

Element115s4 · Answer

Good troubleshooting is important but there are reasons things are called 'supported'.

In theory, I should be able to drop a Gen14 CPU into my XPS 8950 but it's just not supported because Dell made that decision (the hardware is fully capable).

You can do diags all day long and it won't matter.

XPS Desktops

XPS 8960, troubles installing 64 GB ram

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