I've had an old dell pc sitting around dormant for a while so I had the idea of taking the 120mm Nidec BetaV fan out of it and putting it on my current cpu cooler to do a push-pull arrangement.
Although after installing it, it isn't detected by the bios and doesn't spin at all. It uses a 5-pin connector, although one pin doesn't have a wire attached to it, so I just plugged it into a 4-pin header on my mobo (Asus M5A97-Evo R2)
Also, the fan itself is slightly thicker than a standard 120mm fan, if that's any help
What's the issue here?
Edit: the atx board bit in the title is slightly irrelevant I guess, just 'modern board'