[NAME]​ , glad to help out.  The 3620 can take both 6th gen and 7th gen CPU.  The memory clock will also run respectively at 2133 MHz and 2400 MHz.The i7 CPU can also be used for testing your other PC (XPS 8920) as well.
2133mhz is the memory speed of a precision 3620,  but what if I use 2400mhz, will it work? I'm guessing it'll run at 2133mhz, right?
Can a Precision 3620 run on 2400mhz memory?