**DIMM Not installed** despite having RAM present
I have a Latitude E6440 (i5-4310M/AMD 8690M 2GB/HD 4600) I am working on qualifying as a replacement for my i5-4300M/HD 4600 model, which has issues with the motherboard USB ports and it is showing the early warning signs of failure. Due to the early warning, I am preparing to get a unit ready so I can replace it and then use the old one for parts - these boards are about as much as the systems, so replacing the board doesn’t make sense.
However, when I was qualifying the machine I noticed a weird firmware level issue where if I Ctrl+Alt+Delete out to reboot, it “sleeps” instead of restarting. When this happens, the machine boots but shows **DIMM slot empty** despite RAM being present. This has happened with new Yongxinseng and Crucial Mac RAM, so it has happened with 2 sets so far. I also tried some known good Ripjaws with the same effect.
I have also put a E7440 IPS LCD in, so I went back to a known match from the E6440 series (768p). Even when I go back to the “correct” LCD (even though this shipped with FHD, but I had to reuse a screen because of Covid), it still occurs. I have also disconnected the trackpad, WiFi switch and volume buttons with no change. I have also tried without the wireless card - again, no change.
I have also pulled the CMOS battery and installed the A24 BIOS as well, and it’s still happening. At this point, I am stumped and am seriously considering a early disqualification as the final replacement system.