So I never solved the problem but I found something that completely kills the two noises I was getting.   Let it be known, this thing removes 60 cycle hum and EMI from the guitar signal chain.  
Hello, I purchased an XPS 8940 to record music and my guitars and microphones are picking up horrible EMI from the 500w PSU within a 20 foot range. Loud electrical noise is audible whether I am recording a guitar or with microphones. This issue does not occur with other computers using the same recording chain and the noise is at its worst when the microphone or guitar pickups are pointed directly at the PSU. I sent it back to Dell and they swapped the PSU but the problem is still there. It is not clear to me from the search history if anyone has successfully upgraded the PSU to a non-Dell model that doesn't leak EMI? Has anyone had this problem and managed to resolve it or upgrade the PSU?
XPS 8940, PSU bad EMI