|Upgrade your BIOS, turn off cool n quiet in the BIOS|
You may want to unscrew the fan from the new cooler and swap it with the original dell one, if it fits. It will be a much higher RPM fan then the dell one.
See your problem is that AMD motherboard already come with the CPU cooler mount and your dell does not use the same style clip. The dell uses a back plate and the cooler screws in. AMD uses a clip to a bracket.
Other then that you will have to find an after market heat sink that has the motherboard mount.