CPU cooler won't have any issues in that case of yours.
In terms of a modular PSU check these out:
http://www.4launch.nl/shop/#p-4-productid-123847
http://www.4launch.nl/shop/#p-4-productid-081814
http://www.4launch.nl/shop/#p-4-productid-120025 (I would go for this one)
In terms of using greater than 750W you really need to be looking at multi GPU.