Is it normal for the OC frequency to dip every other second while gaming?

I have a 12700k that I disabled the E-cores for and set the clock for all the cores at 5.1 GHZ. When I use Cinebench r23 the cores stay at 5.1 GHZ but when I play a CPU intensive game while using MSI afteburner I see that every other second the cores dip to 4.6GHZ but then jump back to 5.1 over and over again. Is this normal?