I’d suspect that the problem with low-level client-side libraries – not necessarily hardware-related. I’ve had corrupted rendering/display of web pages when I had a couple of hundred tabs open while running Firefox (GNU/Linux) on my old computer with 4GB RAM. Sometimes pressing “refresh” would resolve it or switching to another application and then switching back.

Memcheck never reported any problems with the RAM itself. I haven’t experienced any such problems after installing the Auto Tab Discard extension which allows me to have lots of tabs opens without suffering excessive memory pressure.