Trouble adding second DIMM to Optiplex 3040

What is the mfr. and model # of the original RAM as well as the aftermarket RAM?  Uploading photos of the RAM can also be helpful.

The 3040 will take DDR3L-1600 UDIMM, 1.35V memory.

Jumper is CMCLR, located at the edge of motherboard, about midway of the blue PCIe x16 slot.  You will need to borrow a blue jumper located next to SATA ports.

I tried this but no result.

It is an Optiplex SFF Model D11S. Presently there is one Kingston 8GB stick in the machine (picture included). The new memory is also Kingston and identical configuration.

The photo shows SK Hynix RAM, which Dell often uses for their OEM.

If brands of RAM are being mixed, sometimes some Dell's won't take that for no known reason.

And then there's Kingston's KVR (Kingston Value RAM).  It's hit or miss in Dell's.  It doesn't work for some and some others have praised it.  If you have KVR, "KVR" will be in the model number.  Other Kingston RAM is ok.

Suggestion:  Please try a different brand as a pair.  Crucial is guaranteed to work in Dell's and has a lifetime warranty.  A good way to save money is A-Tech RAM, which also has a lifetime warranty.  I've used A-Tech for years in 2 different Optiplex's and now my current Precision.

I think SFF and MT have the same RAM.  I don't know yet which one you have.  You can always go to crucial.com.

By the way, I was able to just add  A-Tech RAM to the SK Hynix in my previous Optiplex 7010 and in my Precision 3620.

Optiplex 3040 A-Tech RAM list on Amazon 

We had bought two of the Kingston and tried installing them as a pair. 

The reason they didn't work because they are 1.5V RAM.

Get the memory with 1.35V

I found another stick of 1.35V Crucial memory and that didn't work. We are just going to replace the machines as troubleshooting this seems like it is going to cost too much time and these are older machines. Thank you for trying to help nevertheless.