Unfortunately no. Only Dell proprietary psu works for 8950.  The proprietary 10 pinout is not yet deciphered and no adapter is available to connect non-Dell psu to pc.  Try ask Dell to ship you a different model of 750w psu and send back the noisy one.  In my experience Dell is quite good with CRU (customer replacement unit). updated list of Dell oem 750w: MP23Y Acbel 750W (Aurora R13/R14, XPS 8950)M92DC Chicony 750W (Aurora R13/R14, XPS 8950)5TVR6 LiteOn 750W Platinum (Aurora R13/R14, XPS 8950)FT44X LiteOn 750W Platinum (Aurora R13/R14, XPS 8950)NW4C3 LiteOn 750W Platinum (Aurora R13/R14, XPS 8950)M2G8X LiteOn 750W (Aurora R13/R14, XPS 8950)
Hi, I am very disappointed by my new XPS 8950. The PSU fan is very noisy (independently of the workload). I like to work in quiet environment and I will have to buy another computer or another PSU. Note that the Dell support has been really nice and reactive. They have sent a technician to change the PSU but it appears that the new PSU make the same noise which is just unbearable for me. I bought the XPS line considering it was premium material. I guess that I can't be refund since the machine was deliver 4 months ago.
XPS 8950, noisy PSU fan, #2