Motherboard isn't an issue, but tall ram can cause problems yes. The D14 front fan can be mounted higher up, above most tall ram heatsinks, just looks a bit weird, don't think you would get away with it on the 14cm front fan models. Almost all coolers can have the front fan relocated to the back. Also the ram heatsinks can be removed and replaced with something less extreme.
I have overclocked ram, no need to have heatsinks on them. Mine are the Samsung Green.