I've recently made some major modifications to my rig, including replacing the noisy fans on my video card with some quiet ones, and changing the positioning of my fans. One of my goals was to add a 120mm fan at the front of my P183 case to blow across the GPU to help keep it cooler and try to vent some of the hot air out the back of the case.
I decided on a 120mm scythe 800rpm fan based on its noise profile. Overall i'm decently happy with its noise output. However, I was sorely disappointed at the results on the GPU. It did not decrease in temperate at all. After placing my hand over the gpu to see just how much airflow was coursing over it from the newly installed fan, I realized that there was almost NO air reaching it. I had to take the fan out, run it bare to find out exactly why - the fan does not blow "straight". Here is what i mean.
Bottom line is, the fan blows most of its air diagonally out to the sides rather than straight ahead. Most of the airflow is hitting either the bay above it where the DVD drive sits, or the separation area below it where the PSU lies. Very little actually goes straight out and hits the GPU.
Now, I can probably counteract this affect by getting a high RPM model that would blow SO much air, that enough will eventually reach the GPU. However, that would defeat the purpose of a nice quiet rig. So my question is, does anyone know of any nice quiet fans that tend to blow more horizontally straight? I assume this has to do with the shape of the blades.