I just bought an Aurora R7.  The spec for the CPU as below.  Original is 2.8 GHz but on Dell's website stated that I can boosted to 4GHz.  I went to the bios and the OC and XMP memory were grayed out.  

8th Gen Intel® Core™ i5 8400 (6-Core, 9MB Cache, up to 4GHz with Intel® Turbo Boost Technology)