Dying video-RAM chip(s)?

Could you please elaborate a bit more. I suspected this myself, but could you give me some intuition (or a link to some reading) how ram chips can actually fail? My idea of Ram ( as well as of early days CPUs) is that they should actually last almost forever. These days, when we are close to the nm scale (+ very high temperatures / frequencies) I could imagine how material erosion / diffusion etc may actually damage hardware -but with these old chips - any idea how they can fail (and any way to prevent or fix that? thanks

or just a ESD damage.

or just a ESD damage.

but why and how? Remember, only a few days ago, I was swaping and alternating this card with the newer Trident one. And both cards would just work fine.

PC hardware doesn't died instant by ESD. Sometime works it fine for few weeks or hour or months (whatever) then it dies suddenly by pre-damaged ciruit.

Electromigration. It causes intermittent errors before a complete failure of the chip.

Aui wrote on 2024-06-23, 04:38:

Any ideas what could be the problem ? (I already removed / contact sprayed and reseated all chips twice)

Your picture looks like the graphic chip receives complete garbage from video RAM, but is perfectly able to generate a text-mode picture. Does the screen content change during POST? If not, my guess in on the write enable line (/WE) being broken. Kinds fo /WE being broken include /WE shorted to VCC, or the trace interrupted, the solder joint of the /WE pin of the Realtek chip being broken or (of course) the Realtek chip being broken and unable to drive /WE any longer.

Looks like a video RAM problem, or ISA bus speed turned up too high (?)

Well, I have not done anything to the ISA Bus speed. Unfortunately I also do t know how to diagnose the WE line. I noticed that several pins on the Realtek chip are slightly corroded ( will check that later inder the Mic). I will also check if I can find other Ram to try to replace some chips