phoenixnap.com/kb/single-vs-dual-processors-server

The backbone of any server is the number of CPUs that will power it, as well as the actual model and the type of the CPU. From that point, you add the needed amount of RAM, storage and other options that your use case requires.

A CPU (Central Processing Unit) is a piece of hardware responsible for executing tasks from other parts of a computer.

A Core is a physical part of a CPU. Cores act like processors within a single CPU chip. The more cores a CPU has, the more tasks it can perform simultaneously. Virtually all modern CPUs contain multiple cores now. This enables the execution of multiple tasks at the same time.

Threads are like paths your computer can take to process information.
If a CPU has six cores with two threads per core, that means there are twelve paths for information to be processed. The main difference between threads and physical cores is that two threads cannot operate in parallel. While two physical cores can simultaneously perform two tasks, one core alternates between the threads. This happens fast so that it appears that true multitasking takes place. Threads basically help the cores process information in a more efficient manner. That being said, CPU threads bring actual, visible performance in very specific tasks, so a hyper-threaded CPU might not always help you achieve better results.

Single processor servers run on a motherboard with one socket for a CPU. This means that the highest core count CPU available on the market determines the maximum core count per server. RAM capacity constraints with single CPU configurations remain one of their biggest drawbacks.

The most apparent distinction between single and dual-processor servers is that the motherboard has two CPU sockets instead of one. This is followed by additional benefits such as the massive amount of PCI lanes, two separate sets of cache memory and two sets of RAM slots. If the specific motherboard has 24 memory slots, 12 slots belong to the first CPU and the other 12 to the other CPU. In cases where only one CPU slot occupied, the CPU cannot use the other set of RAM sticks. This rarely happens since dual processor servers always have both slots occupied. Dual processor servers and multiprocessor systems, in general, are the best options for space-restricted environments.

While dual CPU setups pack enormous core counts and outshine single processor servers by a large margin, some tests have shown only a marginal performance increase over single CPU configurations with similar core count and clock speeds per chip. This refers to the circumstances where two CPUs worked on the same data at the same time.

On the other hand, we see immense performance boosts in dual processor servers when the workload is optimized for setups like these. This is especially true when CPUs carry out intensive multi-threaded tasks.

www.techsiting.com/cores-vs-threads/