[KLUG Members] re: PCI riser card causes machine not to power on

[Adam Tauno Williams]

> > Subject:
> > [KLUG Members] PCI riser card causes machine not to power on
> > From:
> > Kevin Mitchell <kevin at godzilla.iserv.net>
> > I'm trying to use a gigabit card in one of my Linux servers (it's a 
> > clone).  It had a 3 slot 32 bit PCI riser card in it and I replaced it 
> > with a 1 slot 64 bit card.  After doing so, the server won't power on. 
> > If I remove it, it powers up with no problem. Anyone run into 
> > something like this before?
> Um, I'm confused.  you did what?  If I'm reading this right you had a 
> clone motherboard, that was a small formfactor (NLX or something?) where 

Not neccesarily.  Rack mount units of 3U or less frequently use a PCI
riser card to orient cards parrallel to the motherboard, rather then
vertical (an orientation in which won't fit).  In fact, to have any PCI
slots they have to do something; for instance 1U units usually have two
1 slot PCI rises so you can add two PCI cards;  you can do this with
most stock ATX boards.  What is interesting about risers is that each
PCI slot has a dedicated interrupt channel so you can't just slap a 3
slot riser in a PCI slot or all three cards will be on the same
interrupt and wackiness will ensue.  Then you have to whole 3.3v vs. 5v
thing... ughh.

> the PCI slots are on a riser rather than the motherboard.  And you 
> replaced the riser with one that had a single 64 bit PCI slot?  Sounds 
> like a really odd motherboard.  What is it?