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...