No, Pro means it's the standard clock, non-pros are underclocked
The chip was designed to go around 400MHz, they tested it, sure enough it ran fine at 400MHz. Even though they really didn't need a fan, they put one there just to be safe.
Then they sold the same CPU underclocked and probably undervoltage, as the non-pro. The underclock is the safety factor so they don't use a fan.
128MB Pros come with 3.0ns or faster RAM, non-pros come with 4ns or slower RAM. Usually 5ns, which can't be effectively clocked beyond 200MHz (DDR400).
Funny thing is, the 256MB Pros also come with the cheap RAM, but that's so they can get the price down.
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