I just got a Dell Poweredge 800 and I changed out the factory PSU because it ran its fan constantly. I changed some pins on a 500W Dynex PSU and got it to work. The only problem is the stock Dell PSU had a fan on the back of the PSU while the new one has a fan on the bottom. The fan is large but it is blocked by the giant CPU air duct. I will try to post a pic or a link for the pic. Is the bad for the power supply or is it plenty of room?
pic: https://drive.google.com/file/d/0B31fInaizK8MQ3RqRko0b0hoS1k/edit?usp=sharing
pic: https://drive.google.com/file/d/0B31fInaizK8MQ3RqRko0b0hoS1k/edit?usp=sharing