As a gaming rig, your system is ... not optimal. Dual-Socket CPU solutions are not that well supported outside the professional workstation/server market; Games will use only one of those CPUs (and likely not that many of its cores). And, well, they're Xeons: While very capable, they are not known for their blistering IPC, which is still something games need.
The Dell 0D883F is a single socket board, though? At least that's what the Internet tells me... Is this system a Dell Precision T5500?
And, well, as I mentioned before: this Xeon should effectively be a repackaged i7-990X, maybe with some better silicon quality.
Xeons on this socket are a popular low cost part often used in bugdet used gaming rigs, as long as you've got access to cheap 1366 boards, and they can still deliver some decent performance, although it's first generation Intel Core so there is a lot to be desired. There are a couple threads
on this family of CPUs doing... well enough with VR games, although with some drawbacks. So I guess that as long as you don't play CPU intensive titles, you're fine.
As for upgrade paths... Well, with such a platform you'd normally overclock this CPU and maybe try using faster RAM with it, but this will bring you only small performance benefits, and probably is impossible on this motherboard anyway.
One thing I'd want to mention is that you're using an external USB SSD, but the motherboard has got USB 2.0 only; that means that while your SSD should be able to have read speeds of up to about 500MB/s, the USB 2.0 interface will effectively limit that speed to about one tenth of that. The solution would be to use some USB 3.0 PCIe expansion card, although it'd probably be cumbersome to access. Eventually you could try seeing if you can pull the drive out of the USB case and connect it directly to your motherboard via SATA interface. This won't improve performance but will speed up data transfers and possibly reduce loading times.
Generally, if you're looking for some considerable performance improvement, there's no way around replacing the platform (motherboard, CPU, RAM) for something more modern. And if this is a Dell Precision T5500, that means building an entire new computer. Except the graphics card, storage and any accesories you might be using.