I have an Intel G5 running Snow Leopard - I got a LaCie eSATA II PCI Express card and the Mac does not see it. I tried all the slots and it sees the graphics cards and video card in any of the slots but not the PCI. I installed all the new drivers, LaCie says its a computer problem.I dont have any other problems with the computer (at this time) and I don't have another G5 to install it into. Any suggestions? I sent the card back and had it replaced but still nothing.
As was already mentioned, there is no Intel G5, so I'm going to assume you have just a Powermac G5.
Most G5s had PCI or PCI-x, and NOT PCI-e. Unless it's one of the last run of dual or quad core G5s from late 2005, your card will not work, no way, no how.
Of course, having typed all of that, you mention running Snow Leopard. If you mean 10.6x Snow Leopard and not just 10.5x Leopard, then you must have an Intel and not a G5, so what I said is meaningless. Next time be less ambiguous and people can help you.