If you can afford to go custom, the do so, AIO's are limited and perform as well as high end air coolers. The H100i also doesnt cool as well as a H80i.
If I were you I would wait for the Swiftech H220, it is an AIO cooler but has native support to put an extra radiator, pump and more GPU blocks. It will launch at $140 so just a bit more expensive than a H100i
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