It wasn't! Literally this listing Intel Core i7-9700K Desktop Processor 8 Cores up to 4.9 GHz Turbo unlocked LGA1151 300 Series 95W https://www.amazon.com/dp/B07HHN6KBZ/ref=cm_sw_r_cp_apa_i_lXwCDbF3QFM77

I paid full price - not used or anything weird.

Called who. Is this Amazon themselves, or a marketplace seller?

I see Amazon has multiple sellers, but if you got this with "Ships from and sold by Amazon.com" (or something like "Dispatched from and sold by Amazon.", seems to vary between the different country sites) I would expect a full retail box as pictured.

You can check the warranty status with Intel (I think you can get the numbers off the CPU... Normally it is on the box...), I believe only the retail CPUs get the 3 years. https://supporttickets.intel.com/warrantyinfo . I think but you should probably clarify, that Amazon only provide something like 1 year cover for items they sell themselves, and I am not sure for marketplace.

https://www.amazon.com/gp/product/B07HHN6KBZ/ref=asin_title?ie=UTF8&psc=1

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I havent found anything that mentions the OEM part. You're right, it really doesn't mater. I was just hoping for the shiny box :(