PCI 2.1 spec

[Ben Yurick <byurick@keithley.com>]

Hi all, I have a couple of questions for all you PCI guru's out there.

To my astonishment, I found that the PCI 2.1 spec does not require the
3.3V
power pins to be enabled on motherboards. It encourages manufacturers to

enable this power but does not require it. I have noticed that newer PC
motherboards (say, from 1998/9) do indeed run the 3.3V power onto the
PCI connector.

I have developed a PCI data acquisition card that needs to pull the 3.3V
off of the
PCI connector. My dilemma is now the marketing of this card.
Questions:

1) Does the PCI 2.2 spec enforce the availability of 3.3V on the
connector?

2) How many PCI enabled PC's out there have to play games to enable the
3.3V
on the PCI connectors(change power supplies, jumper regulators etc..)??
Any ideas about when most motherboards started running the 3.3V to the
connectors?

My PCI product uses the 5V signaling environment but also taps the 3.3V
for lower
power/priced parts.

I know that these questions are manufacturer dependent. But, how then is
anybody selling
3.3V PCI cards to the general public? Since in general, the public will
not have the 3.3V
available(older systems).

Please, anybody, I would appreciate any comments, experiences or insight
into this matter.
I would like to get a grasp on what the market conditions are in terms
of 3.3V enabled PC's
to possibly avoid putting an onboard regulator on my product.

Thank you!

Ben Yurick
Design engineer
Keithley Instruments.