Hi So Afraid. I can't give you a complete answer, but will make a couple f observations that might lead to a solution. First the analog/digital signal is generated by a digital monitor when it can't find a signal, and so searches for either an analogue or a digital source until it finds one. This means that during this message display your computer just isn't working.
NVRAM isn't the new RAM you installed. NVRAM is Non-Volatile RAM, i.e. it doesn't lose it's data when power is removed, whereas the RAM you installed does lose all it's data - i.e. it is volatile. Non Volatile RAM is the type your BIOS is written to, it's also used in various other parts of the computer.
I think that what might be happening is that something is causing the computer to start very slowly. This could be the PSU, motherboard or something else. The only way to find what it is might be to unplug everything from the motherboard except the PSU, processor, graphics card, memory and power switch to see if that speeds things up, and then add a component at a time until you find the culprit.