Welcome to the Tech Report!
TR's
System Guide is an excellent place to start looking at components.
The top-performing CPU for most games is currently the $323 four-core Intel Core i7-7700K. You can get quite satisfactory gaming performance from a six-core AMD
Ryzen 5 1600X for $100 less. There are much more expensive
processors available to build a High-End DeskTop or Workstation, but spending an extra $1000 or more for many more processing cores and a matching motherboard doesn't improve performance in the large percentage of current games that have relatively few program threads.
Building a gaming PC today, I would pair a Core i7-7700K with a motherboard like the
$160 Gigabyte GA-Z270MX-Gaming 5 or the
$145 Asus Prime Z270M-Plus. If I were building a new PC a couple of months from now, I would likely choose a six-core Intel Core i7-8700K CPU and a motherboard with the Z370 chipset, but those products are not yet available.
The
$230 six-core AMD Ryzen R5 1600X offers one and half times as many cores as the Intel Core i7-7700K for less than two thirds as much money when paired with a motherboard like the
$92 -10MIR Gigabyte GA-AB350M-Gaming 3 or the just-released Asus
TUF B350M-Plus Gaming. The
$450 eight-core AMD Ryzen R7 1800X offers twice as many cores as the quad-core Intel Core i7 at the same cost for CPU+motherboard. A small percentage of currently-available games really take advantage of the additional processor cores.
Unfortunately, the current speculative Etherium bubble has caused a world-wide shortage of GPUs for gaming, especially the mid-range AMD Radeon RX580 8GB gaming graphics cards. Miners trying to cash in on the craze before it crashes have bought up so many gaming graphics cards that prices have more than
doubled in the past four months.
If you have plenty of funds available for your gaming PC and you intend to play games at 3840x2160 or 3440x1440 resolution, then the top gaming graphics card is a
$750 GeForce GTX1080Ti paired with a
$1200 Asus ROG Swift PG348Q or
$1300 Acer Predator XB321HK monitor with G-Sync. At 2560x1440 resolution, I recently purchased a $407 Radeon RX Vega 56 paired with a
$650 Samsung C32HG70 monitor with FreeSync2. The recently-released
Radeon RX Vega 56 and 64 are in high demand and have been marked up significantly by the
retailers who have stock available. If you intend to play games at lower resolutions, you don't need to spend so much on a graphics card. A
$270 GeForce GTX1060 6GB is sufficient for gaming at 1920x1080.
Note that any new graphics card is likely to become obsolete in three years, while improvements in the other components in a gaming PC have been so slow in recent years that a six-year old PC with a new graphics card is still okay for most gaming.
Once you've selected CPU+Motherboard and a GPU, you'll need some other pieces to have a complete system.
2x 8 GiB of top-rated PC4-25600 memory that works well with Ryzen will set you back
$188. I'd probably go for 2x 16 GiB for
$260, but that's more than you need for most games.
$220 will buy you a good half-terabyte PCIe NVMe SSD.