The machine gives a 2,5 post code. invalid memory. Why is this memory invalid? It has been tested in other machines and is in known good condition. The machine shipped with this memory:
370-AGEI : 16GB (2x8GB) DDR4 UDIMM non-EC C Memory
Part Number: 9CXF2
Description: DIMM,8GB,3200,1RX16,16,DDR4,NU
The memory is the same speed and the sticks are installed in the correct matching channels. It will not boot with any stick of the new memory installed. Any guidance would be appreciated.
It may be the same speed and size but not the same manufacturer. Dell systems are touchy about RAM and Crucial is the most compatible with Dell systems. That RAM is available here.
I am not a Dell employee...I am forum volunteer
Serious work on an E5430 and constantly building and working on an i5-6500 Desktop
You linked an optiplex 780 manual by mistake, but I do thank you for the Crucial recommendation. This machine was shipped with 16B of DDR4 3200 and lists a maximum of 128GB.
It is recommended by users here to buy ram from Crucial. They specialize in Dell ram. Compare the specs here. Even with the same specs some other ram doesn't work.
If your new RAM won't work without previous RAM installed, it may be incompatible. Could be something as simple as a voltage difference.
Not sure how your search was, but some people seem to shop for RAM using specs, which is ok. But it's good to add the Dell model in the search term.* That way, if it's in the RAM description that the RAM works with your Dell model, the seller has to back it. When shopping RAM from Crucial, their website makes a person enter PC model before it says what's compatible. *Specs can still be compared.
Crucial is guaranteed to work in Dell's and has a lifetime warranty.
JOcean
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Posted August 11th, 2021 12:00
It may be the same speed and size but not the same manufacturer. Dell systems are touchy about RAM and Crucial is the most compatible with Dell systems. That RAM is available here.
I am not a Dell employee...I am forum volunteer
Serious work on an E5430 and constantly building and working on an i5-6500 Desktop