Why my HTC One M7 running stock, locked, s-off, not rooted very HOT!??

I wish someone can help me with my phone getting hot pretty fast after a minute of using it. :(
I'm not installing/running any intensive apps or games just a few messenger & social apps people normally use.
Its really-really hot especially when i make video call, I mean I can't hold it with bare hand :eek:

Never touch the recovery, bootloader or ROM, as you can see its at original factory state (i think):
(bootloader) version: 0.5
(bootloader) version-bootloader: 1.61.0000
(bootloader) version-baseband: 4T.35.3218.16
(bootloader) version-cpld: None
(bootloader) version-microp: None
(bootloader) version-main: 7.19.401.51
(bootloader) version-misc: PVT SHIP S-ON
(bootloader) meid: 00000000000000
(bootloader) product: m7_ul
(bootloader) platform: HBOOT-8064
(bootloader) modelid: PN0710000
(bootloader) cidnum: HTC__J15
(bootloader) battery-status: good
(bootloader) battery-voltage: 4109mV
(bootloader) partition-layout: Generic
(bootloader) security: on
(bootloader) build-mode: SHIP
(bootloader) boot-mode: FASTBOOT
(bootloader) commitno-bootloader: dirty-0e2a13e5
(bootloader) hbootpreupdate: 11
(bootloader) gencheckpt: 0

Is there anything wrong with my M7...??? Please Help :confused:

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