2017 iMac is out of memory

If you have a 27" iMac from 2017 you can add additional memory modules yourself by following these instructions: Install memory in an iMac - Apple Support (CA)

If you have a 21.5" iMac you won't be able to upgrade the memory. You might find an Apple Authorized Service Provider to do it but it would be costly and more than that model is currently worth.

If you do have a 27" model only purchase RAM modules from either Crucial.com or OWC (MacSales.com). Macs are very particular about RAM quality and those two suppliers are the only that consistently meet the requirements.

Hi there -

I think there may be some confusion on memory and storage. Memory, also known as RAM, allows open apps and files a place to run, while storage stores all your files, apps, libraries, etc. It sounds like your Mac has 8 GB of memory and 1 TB of storage.

To make sure your Mac is running OK, you could follow this procedure:

To start, let us know what model your Mac is and what version of macOS you’re using. The simplest way to find out is About This Mac, available by choosing About This Mac from the Apple menu  in the upper-left corner of your screen. 

Next, share a screenshot of your Mac’s storage information. In the Finder, choose Go > Utilities, then double-click the Disk Utility icon. (Disk Utility is located in the /Applications/Utilities folder.) Alternatively, click Launchpad in the Dock, type Disk Utility in the search field, then click the Disk Utility icon. Once Disk Utility is open, take a screenshot of the information it automatically opens to, which will be your startup disk. Next, select View > Show All Devices in Disk Utility and select the non-indented disk entry—it’s at the top of the hierarchy. Then, take a screenshot of the newly selected entry. Upload all screenshots here. 

Next, use Apple Diagnostics to test your Mac to help determine if there might be a hardware component at fault.When testing is complete, Apple Diagnostics shows the results, including one or more reference codes.

Learn about Apple Diagnostics reference codes

Let us know which reference codes you receive.

Finally, let us know what antivirus, VPN, or cleaning software you have installed. 

-Jack

RE: “All memory slots are currently in use.”

Thus means that all of the physical places to install memory modules are in use; not necessarily that you are running short on RAM. The Memory Pressure graph in Activity Monitor (Utilities folder) can tell you (using green/yellow/red) whether you should consider paying a shop to install more RAM. If you see green (little or no yellow or red) when going about everyday tasks, then you probably don’t need more RAM.

As for your 1 TB disk, if that is a regular hard drive, or a Fusion Drive, as seems likely, then getting an external SSD and using it as your startup disk might be a way to speed up things without having to get someone to go inside the case.

If this IMac is from 2017 and has only two RAM slots, that implies that it is a 21.5” iMac whose RAM slots are sealed in.

MacTracker shows maximum RAM capacity of 32 GB (actual) / 16 GB (official) for a non-Retina 2017 21.5” iMac; 64 / 32 GB for a Retina one. But you would want to have a repair shop do the tricky work of opening the Mac, replacing the two current modules with higher-capacity ones; then sealing up the Mac again.

You cannot upgrade memory, i.e. RAM. 8GB is all you're ever going to have

You can add additional storage space via an external hard drive or Solid State drive. That can be in sizes such as 256 GB, 512 GB, 1 TB (1,000 GB) and etc.