Re: PCI PCB Specification

[Richard Walter <rwalter@Brocade.COM>]

Folks,

PCI 2.2, section 5.1, paragraph 2, sentence 4:  "In one orientation, the
connector is keyed to accept 5V system signaling environment boards; turned
180 degrees, the key is located to accept 3.3V system signaling environment
boards."

So:
a) The statement that "5V & 3.3V are identical ... except for the width of
the plasic at the ends" is wrong.  The width of the plastic at the ends is
the same.  32-bit 3.3V & 32-bit 5V connectors are, by definition, identical,
except for orientation only.

and

b) If there are 32-bit connectors in existence which don't allow 64-bit
cards to fit due to excess plastic at the end, then that is a fault of the
connector company to make connectors to the correct specification, not
the fault of a motherboard manufacturer trying to erroneously substitute
32-bit 3.3V parts for 32-bit 5V parts.

> From: Neal Palmer [mailto:neal@dinigroup.com]
>
> We have seen the same problem with motherboards.  Apparently somebody had
> an overstock of 3.3V PCI connectors and dropped the price significantly,
> and it turns out that the 5V connector and the 3.3V connector (32-bit
> versions) are identical except for the marking for pin1, and the width of
> the plastic at the ends of the socket.
>
> So a bunch of motherboard manufacturers decided to save $0.01 and use
> the 3.3V connectors soldered on backwards.  It's just too bad for all of
> those customers who didn't know what they were buying...
>
> -- Neal

Sincerely,
-Richard Walter
rwalter@brocade.com
Note: I speak for myself, not for Brocade Communications.