Many of the PSU's out there are rebranded, so Dell's might be exactly the same as HP - what you really need to pay attention to is the plug, if they look the same, then you might be in luck. One of the more common ones is what's called "Common Slot", and those are pretty universal from my experience. When in doubt, grab the data sheet for each PSU and just read over them - I know on a couple of the ones I looked at back in the day they had enough detail you could determine whether or not they were compatible. You could also try contacting whoever made the breakout, like Optimizer, Jabberwock, or Sidehack are the big boys, and ask them (whichever one you're using the breakout) - they've probably seen more PSU's than anyone else on the planet, and might be able to tell you easily.
Personally I use a fair number of the DPS line, DPS 1600BB, 2000BB, 2500BB, etc - and the breakout for them is universal in that family of products.
except that I know of none of those guys make breakout boards, couple might sell them. but none of them have any made. its an ebay thing
and I have to correct ya on the common slot thing, hp and dell common slot psu aren't quite the same, its also the difference between the 1200w hp and the 1500w hp server psu, the pins to turn them on is different between those I just mentioned, so to say there universal doesn't always work, universal implies that you can go from one brand server psu to another with no problems, which I hate to say doesn't work and you should know that.
also trying to contact the seller isn't always a grand idea cause theres always someone besides the original person who makes them that sells them also but knows pretty much nothing about it and cannot answer questions about it
