Studio XPS 8000, upgrades

8000 uses lynnfield cpu lga1156 socket. It is quite old although slight newer than core2. To upgrade cpu performance there is not much potential on this socket. To really see an improvement of cpu you need to move up to 8300/8500/8700 or 8900 motherboard cpu combo, depending on your need and budget.  8300/8500 are Intel 2nd/3rd gen, 8700 4th gen, 8900 6th gen.  For a good cpu performance, 8700 components may be the sweet spot more affordable than 8900.

comparing i5-750 lynnfield with Intel 4th gen i5, you will notice near doubling of single thread benchmark and overall cpu mark.  although both are quad core, newer cpu smokes the old.  https://www.cpubenchmark.net/compare/Intel+Core+i5-750+%40+2.67GHzvsIntel+Core+i5-4690+%40+3.50GHzvsIntel+Core+i5-4590+%40+3.30GHz/772vs2236vs2234

For virtual reality need you almost certainly need to upgrade to at least 

• CPU: Intel i5-4590 or greater

https://www.roadtovr.com/how-to-tell-pc-virtual-reality-vr-oculus-rift-htc-vive-steam-vr-compatibility-tool/

you can still use the old ddr3 memory for up to 4th gen cpu if you want.  for good multi tasking max out the memory to 32GB (4x8 GB) will be more than enough for most people. Graphics card upgrade is determined after you upgrade cpu.

Did you read through the Related Topics threads right of your post?

@DELL-Chris M  do you know incidentally whether Dell engineer still has archived documents on original XPS 730 or 730X including master control board pinout and Dell thermal control app?  I wonder Dell could declassify and release the complete technical guide, now that the model is 13 years old.  There is still a niche of users who can benefit from inside engineering knowledge of it.  Thank you for letting us know one way or the other.

The original Dell engineer for those models is no longer at Dell. Any documentation on their PC's is gone. All guides you and we have access to are here and here. Sometimes you can find additional documents by searching for the specific model here and here.

The image had to be smaller, this is the best I could get it =

@DELL-Chris M sorry to bother you. I know this is an unusual one time request.  can you please change my user avatar to this picture of Dell XPS desktop?   https://imgur.com/a/NLUetUC
I am unable to do it myself.  Thanks.

Thank you very much.  It is perfect.