Hmmm, It is hard to predict what will happen when RAM chips become defective. If they actually "die", then you can expect to be told, just as if you add or remove them, but malfunctions are frequently undetected unless you run a memory test.

I would guess that you had "quick boot" enabled in the BIOS so it did not do a RAM check. It saw that the card was still there and moved on. It did not detect any physical change, so it did not run the test you mention.

If the system detects a memory problem you generally hear it from the BIOS "beeps" but if you don't have an internal speaker you won't hear this. Also, your BIOS would need to be set to do a memory test on bootup.

That is one of the reasons I never enable "quick boot"