PCI Blower above or below my video card

[JEMC]

I'm no expert but that will surely depend on which graphics card are you using and how the blower works.

If your card is a reference one (gets the air from below and exhausts it out of the case from behind), and you put another object, the blower or another kind of pci card, under it you can limit the amount of air that can go inside the graphics card making it run hotter. If, on top of that, the blower faces upward fighting with the gpu card for the same air, then your graphics card will get little to no air and you will get in trouble.

Now if you use a non reference card like those that don't exhaust heat out of the case but into it, then a blower under your gpu facing upward makes sense as it will collect the hot air that leaves your graphics card and take it out of the case.

The last scenario would be if the blower gets the air from below. In that case I suppose it would be better to put it on above your gpu too cool the backplate.