@Mick64
Do you know how convection works?
Its base on the density difference of hot and cold air. Hot air is created only near the heat source not every where in the case. Hot air has lower density than cold one and tha t make the hot air to move up.
There is natural convection and forced convection (using fans). Natural convection is a slow proccess. And that is where those fan will help.
Talking about PSU, i think the there wont be much restriction, cause psu fan faces rad's chamber part, which is smaller, than the rest of the rad.
And, if you whana talk about my wc case design, better to do it in my thread.