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RE: 3.3V power rail / M66EN



>2) Any realy world experiences regarding the reliability of M66EN?
>I ask, because I have another (non-PC) motherboard, where the 66 MHz bus
>can be forced to operate at 33 MHz by means of a jumper, *without*
>negating M66EN, which in turn screws my card ...
 
This might violate the PCI Spec.  The state of M66EN indicates the current
state of the bus, and if it is high (asserted), the bus must be running
between 33 and 66 MHz.  If they are running it at 33 MHz (with 66MHz timing
parameters), that is allowed; but it must not drop below 33 MHz or stop, or
change frequency without RST# being asserted.