For some reason, I couldn't sign in with my long time user name so had to create another account in order to reply to your help. My current machine is a Dell XPS 8930 and the tag number is 9SMCOM2. Hope this helps.
Your service tag appears to be 9SMC0M2. (That's a zero, not a capital O.)
I'm a little disappointed that the service tag doesn't lead to a parts list for your specific XPS 8930.
Support for XPS 8930 | Documentation | Dell US
The Setup and Specifications document lists 3 possible PSUs: two 460W, one 850W.
The highest end GPU sold with it was a GTX 1080, which is a 180W card that needs a single 8 pin PCI-E power cable. Its minimum suggested PSU is 450W.
NVIDIA GeForce GTX 1080 Specs | TechPowerUp GPU Database
I hope that means you'd get the PCI-E power cable with any of the possible PSUs.
Suggested graphics cards:
RTX 3060, 12GB. (Don't get the 8GB version. It's not enough cheaper.) Nominally 170W.
RTX 4060, 8GB. 115W.
Both are about $300 at Newegg. The 4060 is a generation newer, and has better performance, even though it's a PCI-E X8 card (vs. X16 for the 3060), and has a lower memory bandwidth than the 3060.
I think I'd suggest the 4060, as long as 8GB is adequate for you. (Should be.) That 115W spec is attractive.
I hope that either card would be an easy swap for the GTX 1050 ti.
XPS 8930 Service Manual | Dell US