I just upgraded my processor from i5-8400 to i7-9700K and it went without a hitch. Original cooler can handle barely new processor then it is running at full load. So you can't even consider overclocking the system.
Question is what might be HP compatible cooler to handle higher heat load?
Noctua's coolers cannot exist with current backplate.
The 880 series used a rather proprietary cooler system by Asetek. Bottom line is, choose the brand you want (providing the radiator will fit if you want an AiO) and know you will have to remove the motherboard and pry the existing backplate off. Its glued on with strong double sided tape. Just don't mistakenly try to pry the metal plate that's embedded into the board.
Unless you can find a used AiO from a parted out 880 on the web, I would rather go with a name brand.
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