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Open coolers do better than blowers on most DAN A4s I have seen by different users. Vertical fins help air exit to the bottom and top of the case, which are ventilated. Or if you have a 15x90mm fan under the motherboard then the air can easily be pushed from bottom to top through the fins. The Gigabyte Gaming G1 is a good example of a card with vertical fins and with dimensions that fit the DAN A4, but higher end cards (2080\Ti or something) might have a wider than 2 slot cooler implementation.