As I posted before, comparing the specs is one of the least important areas of difference between PC gaming and console gaming...and even if you do you can't replicate the 1X in terms of performance and you certainly can't get anywhere close when you allow for form factor, quietness and labour costs.
Anyone posting possible builds, or arguments about which gfx card it equates to is completely missing the point
How do you even know how quite the Xbone X is? Jeebus, people. My PC is a hell of a lot quiter than my Xbone S when gaming. It is about twice the size though.

As usual this threads relaly aren't about: can you run games as well as X console with Y budget, It's about scoring points in system wars.
Can you do the same performance for $499? We don't knwo for sure yet, but by November? Probably yes.
But does it have UHD blu-ray? No. And the 50 people who care about UHD Blu-ray probably aren't looking to build a PC for this purpose.
But does it have an ultra compact form factor? Not for that price, no. Does the XboneX have the form factor of my Steamlink? Or my Nvidia Shield?
But those cost more!! Well yeah, and so will an XboneX during it's lifetime over a PC build.
I don't think anyone is disputing the value the XboneX offers as a media center device. If UHD blu-ray is super important to you, if form factor and TV gaming is super important to you, and you are unwilling to pay more for it, then an Xbone offers tremendous value. I don't think anyone can dispute that.
If all you care about is performance, well PC is going to do it better, stop trying to say otherwise. Even just the fact that YOU get to decide what compromises a particular game makes to reach whatever resolution or performance level you want (vs developers deciding for you) makes it the superior platform where graphics or performance is the key.
Of course if that's all you care about, you're a strange gamer.
I care about PC gaming because of it's ginourmous library of games, many of which not available on the Xbone. And because of mods and superior VOIP, graphics options, etc, etc.
Now I know where the superior media center experience is at. Which is why I own an Xbone S for all my 4K TV viewing entertainment. But my games are all powered by my PC.