Depends what you are using it for. Have a feeling that you were looking at PassMark scores which are linked here.
https://www.cpubenchmark.net/cpu.php?cpu=Intel+Xeon+E5-1660+v3+%40+3.00GHz&id=2412
https://www.cpubenchmark.net/cpu.php?cpu=Intel+Core+i7-7800X+%40+3.50GHz&id=3037
This shows the two CPU's as being relative equivalents but you have to look deeper than the overall PassMark score.
The 1660 has 8 cores/16 threads with a base core speed of 3.0 GHz and a turbo speed of 3.5 GHz. The 7800X has 6 cores/12 threads with a base core speed of 3.5 GHz and a turbo speed of 4.0 GHz. PassMark single thread ratings are 1783 for the 1660 and 2251 for the 7800X.
Gaming usually does not use more than 8 threads and relies more on single thread speeds for performance. This will become even more of an issue should you want overclock core speeds; overclocking is not possible with the 1660.
If you plan on streaming while gaming, the 6 cores of the 7800X will still be enough. Other applications like being a server rely more on the ability to carry out several tasks simultaneously, higher core counts will improve performance here.
For gaming, the 7800X will blow the 1660 out of the water.