You either have a 180w or 240w PSU.  A 120w GTX 1660 is definitely out.  Any GPU cards also have to be LP (low profile).  Some options below. From the Precision 3420 Spec Sheet:  One PCI Express® x16 Gen 3 Graphics card up to 50W Entry 3D cards: Professional 2D cards:
Hello, My office switched to laptops, and I was able to keep one of the old desktops. I am using this as an excuse to try PC gaming for the first time ever! With that, I found the website User Benchmark, entered my specifics, and it seems the GPU is the biggest thing holding me back on the gaming front. I am wondering what are my best options for a new GPU? The only recommendation I have found so far in my google searching is someone who put in a Nvidia GTX 1050-TI, but wondering if anyone has other suggestions. Thank you in advance, and below are the specifics of my computer: Tower: Dell Precision Tower 3420 SFF CPU: Intel i7-7700 @ 3.60 GHz, 4 core - 8 thread GPU: Nvidia Quadro K1200 (plus the base Intel HD6 630) SSD: 512 GB RAM: 32 GB - 4x8GB - DDR4 @ 2400 MHz   Attached are pictures of inside the case, as well as a screenshot of the user benchmark (brands of some components are guesses). Thank you for all of your help! [IMAGE]Internals[IMAGE]User Benchmark  
Dell 3420 SFF GPU Options