Yes, the cooling solution blocks the slot below it. So I essentially have a triple-slot video card. This is actually somewhat annoying because the shared IRQ assignments on this motherboard mean that I can only use 2 PCI cards... which is barely enough for me to scrape by (sound, ethernet).
I believe the limiting factor is the thickness of a standard 92mm (or 80mm fan). The bracket is designed to match the thickness of the fan, and the industry standard thickness of these fans is thicker than an expansion card bracket.
But overall I'm happy with this solution because I can keep my Voodoo3 bone stock, while decreasing the chance it'll die from heat (this is my childhood video card not I'm interested in paying big bucks for a replacement!!).