Provided there's not something physically wrong with the hardware..
First make sure all your power connections, 24pin and 4/8pin connectors are in place.
Make sure the Intel cooler is properly plugged in and propperly seated.
Try resetting the bios to factory. Since it wasnt detecting the fan of the Evo, something might have gotten tripped up in a protection mode.
Now assuming this works, keep the Intel fan plugged in and go in to bios. The Evo has a very slow RPM when its at idle. Its not uncommon for this to register as too slow by the bios and it turns itself off as a safety measure. Look for an area in cooling, or temp monitoring area of your bios and see if it allows for a custom fan speed for the CPU cooler. If it does set it to the lowest limit, it'll probably be somewhere around 4-500 RPM. This should be enough to allow the computer to start with the Evo in place.
Thank you for contributing. I would love to go into bios, but the PC won't even boot up! The power supply fan and intel stock cooler will only spin for a split second, and this will go on forever. Also, my 8-pin CPU connector is completely fine, it is in where it belongs. I'm starting to think I broke the Mobo in the installation of the new cooler, I may have crushed the pins
. I will check and will report back when I know the mobo does or does not have crushed pins.