Retail windows 10 home key for £10. Have used quite a few in the past with no issues.
Sure it has a blue ray player inbuilt. Can't get an inbuilt one to fit that price range I agree with that.
I could mention an extra cost of around £10-15 per game vs PC games, cost for membership. If you wanted to use mouse aim you will need a £100 adapter. but I left those out...
We are purely on about the console itself. Games are not being covered by those costs. You are now deciding to change tact because what you posted before.
And sorry but I've never seen the £10 retail home key. It's £95 from OcUK and £115 from Microsoft direct.
There are cheaper adaptors and MS is working on adding support later. But again that's irrelevant to the costing. The controller needed to use the console would be £48 so the cost of mouse/keyboard then for gaming would need to be proved less than that for a saving but still need to include a price for it.
So my point still stands that the cheapest you can build a system with is £800 for similar spec or even £720 with your magic £10 key (not including student/education discounts etc) that's still a fair chunk more than the console.
I'd also say that the CPU and GPU won't run as well as that on the Xbox because games are not well optimised and even getting smooth continues 30fps at 4K is going to be a tall order on medium settings for the games that are releasing with this console.
I have the Intel cpu you specified for a machine for misses and it struggles with keeping up with gaming because the resources used just to run the OS although haven't tried game mode with W10 since but the low percentile frames drop below 30fps and that was with a gtx 1070 as GPU at 4K medium/high.