A desktop or laptop PC with a good clock frequency and architecture (dual or quad core, or with logical cores/hyper-threading if an Intel processor) and a good amount of RAM is best for a gaming PC that is designed to run heavy and intensive software. This means 4-16 GB of RAM is needed, although the higher number is not truly necessary for most games. Eight GB of RAM is sufficient for most games. A graphics card/GPU that supports DX12 and has a good capacity and clock frequency is also necessary; this means not using an integrated graphics card, but a dedicated graphics card (Radeon, GeForce, etc.). It is also important to note that a computer's CPU clock frequency (i.e. 2.0 GHz or 3.0 GHz) alone does not determine a super-fast PC. Everything from the bus, to the architecture, to the core structure, to the RAM, etc., will help to determine how fast it will run. SSD is certainly desirable in a gaming PC (more on that later).
Dual CPUs are two CPUs operating on different chips (silicon substrate); that is, two CPUs acting in a PC — while dual core PCs have two cores on the same chip (silicon substrate). Each has an advantage, e.g., less distance between two processors (i.e. being on the same chip) is often better as it increases speed of communication between the two processors and thus the speed of processing data, while dual CPUs allow both processors to access the motherboard resources separately (through their own set of pins) without having to share pins. Quad core CPUs have four cores, hexa-cores have six cores, octo-cores have eight cores, etc.
Later generation Intel processors utilize hyper-threading, which is a technology that allows multiple threads per core to process data, resulting in a number of logical processors operating. For online-utilizing software, ping must always be taken into account. Ping is essentially based on proximity to a system that is on a network (e.g. a server), and is the time it takes for a system to get a response to a request. The communication delay or latency results from high ping and causes lag. As a general rule, in photonics, modems/networks which use fiber optics (i.e. light) will transfer data faster than copper wire, so that ping is (relatively speaking) lower. Ping is recorded as ms, where every 100 ms is 1/10 of a second delay, i.e., the wait time for the PC to receive data and update the software based on it. 200 ms is 0.20 (20% of a second) latency, or 2/10 (1/5) of a second latency. Certain software can help to reduce ping to help with better online gaming, such as Pingzapper.
To explain a bit more regarding SSD and the running of software on gaming PCs, it must be mentioned that solid state drives operate as non-volatile memory that is generally connected to the motherboard of a PC, and operates as a PC storage device. Due to operating like flash memory (typically NAND-based flash memory) and not using the hard disk system of HDDs, it loads data into RAM (memory) much quicker, and thus is best for optimal performance in gaming PCs. It is less in capacity (though this is changing), and is more expensive, though current trends are moving toward larger SSDs at lower cost.