Its on the chip itself(manufactured into the same area as the cpu/gpu).
Considering that both the ps4 and xbone use 2.5inch drives I dont really care that they are not upgradable. I would rather just by a 3-4tb external and attach it if needed, the difference between a usb 3 external and a sata 2 hdd are going to be negligible for load times.
Whos the fan OEM? Anything under that black sticker?