If you take a set of tin snips to the case back you can use pretty much any standard ATX psu that has a 20+4 pin main connector.
The Silencer for Dell is different than standard only because it , like the Dell psu , has no switch.
Thanks Delluser. I was under the impression that Dell's had a different wiring setup.
I'm not too confident about using the tin snips. The metal case is encased in a plastic outer, the PSU has no space around it, so anything larger and it will start coming outta the box and I don't want to cut the plastic outer.
Thanks sunny- this was one of the first places I tried, it's a well known site.