how to fix iMac beeping every 5 seconds

Hi mtdavison,

Welcome to Apple Support Communities.

First, take a look at If your Mac beeps during startup - Apple Support. According to your post, it sounds like it is beeping once every five seconds. If that's the case, your Mac isn't detecting any RAM.

Have you recently upgraded or replaced the RAM? What year is your Mac, and what is the specific sub-model? (screen size, model)

-Jack

You either have a bad memory module, bad memory slot, or you are using incompatible third party memory. Macs are very particular about the memory they use so it is best to only use memory from Crucial or OWC.

If you have never installed third party memory and the only memory in this iMac is from the factory, then most likely one of the memory modules has failed.