**The number of cores needed depends on what you do with the PC 2 cores can still be effective for a lot of things. Most gaming PC's today are 4 cores and can go up to 8 cores.
**Clock speed is how fast the Cpu computes, most are above 3.0ghz but ive seen 2.5ghz dual core Cpu's hold up in many applications.
**Cache is where information is stored while computing so higher cache means more information can be processed at any given time.combined with good core speed makes a good cpu.
** Be sure the CPU socket type matches the motherboard.
Graphics card--- GPU clock speed, Amount of available memory, Shader cores, Pixel rate.
**Gpu clock speed is how fast it processes graphics (faster is better)
** Amount of memory (RAM) is how much it can process at once and it uses its own ram instead of system ram. (higher is better)
**Shader cores is the number of cores filling in the graphics(More is better)
**Pixel rate is how many pixels per milisecond are refreshed (higher is better)
Ram--- Frequency, Ram type(ddr2, ddr3 etc.), GB's
**Frequency is the speed of the ram(higher is better but must be supported by the motherboard)
**Ram type is the technology used to build it and the socket type of the ram. be sure it matches the motherboard.
**GB's is the amount of info that can be stored for processing (higher is better). however there is a point of overkill, most gamer do well with 8gb where video editing can go up to 16gb and some even go up to 32gb+ for headroom.
Motherboard--- Socket type, Ram slots, Max ram, Ram speed supported, Chipset, Sound/graphics,
** Socket type must match the CPU you are using/buying
**Ram slots are important for upgrading ram. most boards have 2-4 channels. pick a board that has sufficient upgrade-ability for your future needs.
**Ram speed supported be sure that your board supports the speed of your ram or you could end up with improper ram functionality.
**chipset--- boards with more current chipset architecture are more likely to have a longer lifespan and must be supported by the processor. (or vice/versa the board must support the CPU chipset)
** most boards have onboard sound/graphics and usually are ignored due to dedicated gpu's you may wish to use the onboard sound however.
Power supply--- Watts, Efficiency, connectors.
**be sure that you have enough wattage to power your system. lack of power will cause system failures.
**efficiency of 80+ bronze rated or better is suggested for most gaming rigs.
**Be sure that the power supply you buy has all the proper connectors for the components you need to power.
Case---Fans, Room, Cable management, Expansion slots, Motherboard mounting support, looks
**fans = cooling at-least 2 fans is desired
**room = airflow = cooling more room is better
**cable management means less clutter and therefore better airflow cases with this ability are my first choice.
**expansion slots are where the components are housed be sure to have all that you need.
**motherboard mounting must match the motherboard you have (Atx, Matx, Itx.)
**Looks-- lets face it no one wants to look at an ugly PC.
Hard drive--- Speed, storage, size (physical)
** faster speed means faster processing
**Storage more is better but pick one that fits your budget and still allows you to store all your favorite games.
**size be sure there is room in the case to store your hard drive.
Optical drive--- really the only thing that is important is can it do what you want. play cd/dvd/blue ray, write cd/dvd/blue ray.
Thank you for reading this i hope it helps.