iMac hard drive noisy

No M1 based Macs have a HD installed. You either do not own a M1 based Mac or you do not know what is installed in it. Please click the in the upper left of the display and click About this Mac and it will tell you exactly what you own.

As for the noise, please take it to your local Apple Authorized Service Provider to be checked out. Some Macs still have fans and there is a very small possibility it may be a fan.

M1 iMacs don't use HDD's, so it isn't the drive. What you're hearing is the fan spinning (or possibly fans, as they are available with either one or two fans).

As for the noise, see here - About fans and fan noise in your Apple product - Apple Support

Allan Jones wrote:

Images of M1 iMacs on other sites show one small fan located behind the lower bezel and just left of center.

Indeed- at least for the base 7-core model. The 8-core GPU model has two, located here-

That is what Apple has called it since the early 90's - they still do even though most - if not all - Macs now have an SSD, Flash storage, or similar. There is no longer a spinning drive. A 24"has an SSD. And they are glued/soldered = no moving parts.

It has a SSD, they just don't change the name. 8^)

Images of M1 iMacs on other sites show one small fan located behind the lower bezel and just left of center.