I don't really know anything about Dell's Poweredge machines, but in case you haven't been there, here is a large thread on PCI card compatability with the 1600's at the Dell forums:
link
I only read through a few responses (the thread covers about 3-4 months of posts), but from what I saw, alot of people are having problems adding PCI cards to their 1600's. I hope you can find an answer that will help you out. Good luck.
link
I only read through a few responses (the thread covers about 3-4 months of posts), but from what I saw, alot of people are having problems adding PCI cards to their 1600's. I hope you can find an answer that will help you out. Good luck.