PSA: PCPartPicker is dropping support for E-ATX cases if they list a "up to X" length
https://pcpartpicker.com/forums/topic/323234-correction-p600s-e-atx-support
This is technically bad since many of the cases that lazily slap "E-ATX support" on them cannot necessarily support any E-ATX length since the motherboards vary, so while the Define R6 can most likely hold a longer motherboard than the Lancool One (since the lancool's length isnt listed), if you select a 277mm long motherboard like the Asus Rampage VI, the Define R6 will not be listed as supported but the Lancool One will be.
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The redesign was never a factor in the E-ATX compatibility issues. That's been a thing since motherboard manufacturers started calling their boards "E-ATX" without noting that it's shorter than the official E-ATX length of 330mm. To be fair, they cant call it ATX since the official spec is hard capped at 244mm, and making up a new motherboard size would probably just confuse people....