I have upgraded my PSU in my Dell. It was a nightmare. The PSU that I bought had a power switch on it, and my case only had an opening for where the cord plugged in, so the switch was blocked by part of the case. I had to SAW OFF part of the case in order to get the PSU to fit right. Also, I bought a new mobo for my Dell and I tried to put in the Dell case and it wouldn't fit cause the openings didn't line up. So, I saw them off only to find out that the motherboard is too long by about an inch for the case. I was pissed. I will never buy from Dell again because you simply cannot upgrade them.