Obelisk 875-1023 RAM Upgrade troubles

[madjobber]

Hi,

I've just added 32GB of compatible memory to my Obelisk 875-1023.  However, no matter what configuration of DIMMs I use, if a module is in DIMM slot 3 or 4 I get the memory initialization error beeps (3 long, 2 short).  I've tried to following scenarios:

This machine is currently running Windows 11 Professional.

Original RAM in DIMM 1 and DIMM 2 + New RAM in DIMM 3 + DIMM 4 - error beeps.

Original RAM only in DIMM3 + DIMM4 - error beeps.

New RAM only in DIMM3 + DIMM4 - error beeps.

New RAM in DIMM1 + DIMM2 + Original RAM in DIMM3 + DIMM4 - error beeps.

Alternating New RAM and Original RAM in both channels - error beeps.

New RAM in DIMM1 + DIMM2, with DIMMs 3 + 4 empty - boots fine.

1 Module of New RAM in DIMM1 + 1 Module of Original RAM in DIMM2, with DIMMs 3 and 4 empty - boots fine.

I have ruled out module incompatibility by using both new and old sticks in the same dual channel. The OS supports 64GB of RAM and according the the Obelisk 875-1023 spec sheet so does the Shire motherboard. 

Is it likely that there is a hardware issue with DIMM slots 3 and 4?

Thanks!

[Bill_To]

Hi @madjobber 

Not familiar with this MB. Don't know how HP has configured the four memory slots.

Every dual channel, four memory slot retail MB I have worked with requires using every other memory slot to get dual channel memory speeds.

You could be installing two different memory modules in the same memory channel if HP has modified the memory channel configuration on the MB.

Mixing different memory module brands can cause issues but It does sound like you have a problem when using memory slots three and four. Again, I don't know how HP has setup the correct memory slot population on your MB.

Your problem could indicate a bad memory channel (the CPU memory controller), one or more bad memory slots, or a MB wiring problem between the memory slots and the CPU.

Try one stick of new memory, in addition to the factory config, in slot three and then slot four to see if the PC will POST using a third stick of RAM in either memory slot. Try the HP memory in every other memory slot.. Try the new memory, one at a time,  in the remaining open memory slots.

Maybe you have one bad socket or a memory channel has a problem as previously suggested.

Regards