The Vram is non-volatile memory that the machine uses to store configuration and game play history. The more game you have on your machines, the more NVRAM is used up. I don't like passing the threshold of 92%, but others here say they have not problem going higher than that. I figure as you play with the machine and store play history, accounting information, etc, that it will eventually fill up. These machines were never meant to have the hundreds of games people install on them, so in casino's the utilization rate hovers around 60% typically. I don't really know what happens when you reach 100%, I suspect some kind of lockup that would prevent additional gameplay until some nvram is cleared.