once I get my hands on a 5700 xt challenger Ill measure the thickness of the fans and then plan accordinglyI doubt that you can swap slim GPU fans for 25 mm fans. Even using 15 mm will probably be pretty close to perforation and will get loud.
thank you so much for taking your time measuring this I hoped the heatsink would be completely flat, this will make it a lot tougher using 3rd party fans for it
Here's the measure, not very accurate but can give a general idea, one thing to notice is that the heatsink at the port's side (3 in total), is irregularly shaped, the highest part is 30mm, and it's inevitable if putting a 120mm fan on it, unless you shift the fans to the other side to avoid this piece of metal totally, the rest 2 are all 20mm height (blue circle, another one unseen in the picture).
Got mine in China preordered for 3300 yuan