Consumer loads are mostly limited by single threaded performance, though software is increasingly written for more cores. Best choice for a consumer used to be dual core, now it's probably quad core with thermal limited boosting on less parallel workloads.

It's only prosumers doing lots of transcoding or rendering, or CPU intensive VMs, that typically benefit from increasing cores above 4.

Whereas the server space prizes throughput and much of its workload is trivially parallelizable. On the server, higher single core speed mostly just decreases latency for small tasks; if you're happy with the latency, you can get more cores working on shared memory and potentially get big wins in perf.

There are diminishing returns though, scaling up boxes is expensive and unless it's being forced by software licensing or architectural models, things like Hadoop and Spark for spreading the load across a whole cluster are increasingly attractive. This helps solve the I/O throughput problem too.

The big difference is in the E5/E7 chips.