Chosen Solution
I bough 32 Ram for my mac mini 2018. Installed it step by step, without any problems. The computer starts and works perfectly for about 25-45 min, then the screen turns black and sometime restarts the computer, and sometimes I need to restar manualy the computer to start working again… Update (05/20/2020) this is the memory I bought Memory Maxxer RAM Upgrade Kit Compatible with Mac Mini Late 2018-16 GB https://www.amazon.com/gp/product/B084D5… for my mac : Mac mini (2018) 3 GHz 6-Core Intel Core i5
Sounds like you got a bad SO-DIMM or the wrong ones. You’ll need to open the system up and take one SO-DIMM out then give the system a good run through is it stable? If not swap out the SO-DIMM’s and test again. If its still unstable use the other slot trying one SO-DIMM’s at a time. What did you discover?