Mobo is Asus B150M, Windows Pro 1903, 8GB Kingston HyperX RAM. I got some replacement RAM from a warranty claim (the Kingston lifetime warranty works!) and decided to put it in my system. The RAM was slightly different speed and latency from what I had installed (2666mhz vs 2133mhz, CL15 vs CL14) and with all 4 sticks in, I got nothing, not a beep, no lights, nothing. Pulled out the replacement DIMMs (the 2133mhz sticks) and the system booted again and ran fine. Yesterday I decided to test the 2133mhz RAM by itself and make sure it was good before putting it on Ebay. Pulled the 2666 DIMMs, installed the 2133 DIMMs and again, nothing! Pulled the 2133 and reinstalled the 2666 and again, nothing. I thought maybe the power switch on the case was flaky so I pulled the connector and shorted the power switch pins but that did nothing also. Do you think it's possible my PSU gave up the ghost coincidentally with the DIMM swap? Or is something else going on? I pulled one DIMM and that didn't fix it, I have not yet removed all the RAM to see if I at least get a beep. FWIW, the PSU is an EVGA 500w unit and it's been fine for 3+ years. My system is lightly loaded, using Intel onboard video, Pentium G4500, one M.2 SSD and one hard disk and one DVD ROM and runs anywhere from 3 to 5 hours/day.