I have a few suggestions.

First of all, Microcenter is a great option to consider. Microcenter by and large is also 'regional', meaning they have different stores, and different locations, so it's best to call the store you are looking to purchase from, and also physically go to the store to complete the purchase.

Some things to consider if you are going to 'go to a Microcenter' is to make sure that you get a high air flow case, the case models that we have suggested are very high quaity air flow cases.

Microcenter has a habit of trying to 'deal bundle' with parts that other consumers know not to invest in, including cases with low air flow, or motherboards that have higher than average temperatures.

So just be advised to part replace wisely.

As far as Windows 10 goes, it's perfectly fine to install Windows 10 without a license originally, and run it until you are ready to purchase a license key. The license keys are often very affordable by the way.

Finally we are getting into the subject, of what are your use cases for the computer you are investing in?

Your stated use case is FPS games, which is a specific type of game, that requires high stable frame rates, and to be honest it will also require some good equipment such as a mechanical keyboard, and a quality mouse, and mouse pad.

It will also require a monitor. This is my current suggestion for a sub $600 monitor. Ignore the reviews on the Amazon site, it's a newly released monitor, and DOESN'T reflect the quality of this monitor.

Here is the review of the monitor.

It is 1440p, 160hz, has excellent sdr (brightness), has above average motion blur, has above average font clarity, supports both g-sync and freesync, and it's an enormous 32 inches with a slight curve.

The only negatives to this monitor is that it's a VA panel, meaning that if you are looking at it from a wide angle, it's tougher to see the picture, meaning that it's not great for multiple people to utilize the same monitor.... and the reviewers dock it EXTRA points for this negative.... meaning that this monitor is an INCREDIBLE sleeper for any one person using a computer monitor. I own and have been using this monitor for the last month, and have ZERO complaints. This is coming from someone who bought a 24in TN 1080p 240hz panel from Dell, one of the highest rated FPS monitors available, and then decided to sell it because it was too SMALL.

Finally we get down to the CPU choice of AMD or INTEL. The 3900x is a FANTASTIC workhorse cpu, it's going to game at near the best possible capacity, but it's not the best at gaming.

The INTEL cpu is going to pull an extra 20-30 frames in games because it can be overclocked to 5.1ghz on all cores. Notice there are two cpus listed the i7-10700k and the i7-10700k @ 5.1ghz.

So what does that mean? And why is it relevant to FPS games? It means that in the long run, the 10700k (or any cpu that can clock as high as the 10700k) will perform better in games that rely on mostly single-threaded performance. Games like Valorant, Fortnite, and Apex Legends are all examples of games that are played at low resolutions (1080p), but also require 'high stable frame rates'.. which both requires a nice cpu, and a nice gpu.

Zach's suggestion for the budget amd 3900x build is spot on an extremely versatile computer that decimates intel in the multi-processing benchmark though. So it's totally worth considering if you are going to be doing programming, or film editing, Blender etc.

Here is a more budget friendly i7-10700k build. This is without the GPU, and I do suggest going with the after market 2080 super if you are going to purchase currently without waiting.

PCPartPicker Part List