why have 18 2.6ghz core instead of 8 3.7ghz

[siaan312]

I recently read that the ghz on a processor is per core, meaning on the i7 8700k you have 9*3.7 although they dont add up to what ever that is because programs run on one core.

so my question is, if programs run on 1 core, why have lots of cores but lower ghz? wouldn't it mean programs would work on a lower clock speed?

the 18 core i am referring to here is the i9 7980xe
and the 8 core is well, the i7 8700k (what i have)

i dont plan to buy the i9 as its kinda pointless unless you really want a super computer, but lets say i did want to buy it. why is it better than the i7?
aside from a bigger cache

 

[Shektron]

Because not all applications run on a single core - many, many applications out there today can use make use of as many cores as your processor has, and the performance will scale linearly with the number of cores. So, 18*2.6 is more than 8*3.7, which would mean the 18 core processor would give higher performance in such an application, although that is an oversimplification of the true performance. Still, lots of applications use multiple cores, and it is for such applications that a processor like the i9 7980XE is used.

 

[stdragon]

The two primary factors that drive up the cost of a CPU is speed, and core count. For example, for the same price, you could choose a slower clocked CPU with lots of cores, or a fast clocked CPU with fewer cores. Of course, you could choose something that was in the middle in both speed and core count.

If you plan on doing any kind of transcoding or video editing, you'll want lots of cores. If however, you plan on just gaming, you'll want the fastest CPU you can buy, but keep the cost down with fewer cores. Essentially, a fast clocked Core i5 is the optimal cost-effective choice.

So why go with an i3? You'll get better battery runtime from a laptop with one. They're perfect for the road-warrior that does nothing but use the internet and work on MS Word and Excel documents.