3D Prophet II 64MB, what speed ram?

[music10k]

Is it possible to find out what speed memory is in my 64MB prophet II w/o removing the heat sinks?
I'm wondering because I was able to clock my card up to 230/410 w/o any problems. This seems quite a bit faster than 6ns ram should be?

 

[Fireball]

Rumor has it that some came with 5.5ns RAM. I am also able to hit 410, but I don't feel comfortable at that speed. 390 is good enough for now.