I have actually by now upgraded nearly every single component and not had any issues, for example I changed the Quadro K2000 to a FirePro W7100 which required e

I have actually by now upgraded nearly every single component and not had any issues, for example I changed the Quadro K2000 to a FirePro W7100 which required external power, added a WiFi card, added 116GB more RAM, etc. Sure, the PSU is a proprietary form factor, but that has its own advantages in the packaging i.e. this one interlocks into the case in such a way that there isn't any cable management to be done and it has a push-to-release mechanism that allows it to be switched out in around 5 seconds without unplugging anything. Yes, if I needed to source a replacement I'd have to do some digging and find a DELL one specifically, but it's a trade-off to be aware of. At the moment there are 20+ DELL precision workstations on Gumtree in just my local suburb.