Question black screen on boot with 2 rams installed ( with 1 ram working)

[x4ex]

The computer worked perfectly for a year without any problems, but suddenly it started to show a blue screen, when I turn it on, the picture is black and the computer works, but there is no signal, I tried to clean the ram, to restart the bios as well as the cmos battery, I cleaned everything with the compressor but later it didn't work at all, until I took out 1 ram, I have 2 ram slots (2gb + 4gb) I thought it was up to one of the ram sticks but both ram slots work perfectly as well as both ram memories, only when I put 1 ram memory in any slot computer works normally

 

[drea.drechsler]

Computer specs will help...motherboard, cpu, memory, gpu (if discrete) in particular but also PSU and CPU cooling. But it sounds like you have a mis-matched memory configuration which never works well anyway. Try one module at a time to see if one has gone defective, then each module in each socket to see if a socket is defective.

I'm not sure what you mean by "cleaned everything with a compressor" but using shop air, like that used to inflate tires or power pneumatic tools, can be a very bad idea. It can have moisture or even compressor oil in the air stream but it's also much too strong and can actually break small components loose. If you blew it directly into the DIMM or CPU sockets it's very likely to have bent some of the small contacts. You'd need to have an in-line drier and reduce the pressure a lot before using it directly on electronics.