Q: I can't upgrade to El Capitan as it says I don't have enough RAM (2GB required) - any way round this at all by freeing up RAM etc.

The only way is to upgrade RAM.

If your computer otherwise meets at least minimum specifications for running OS X 10.11

El Capitan, that would be good to research and know beforehand. If the unit is too old for

the newest OS X, the options for upgrade past 10.6.8 are few. Lion 10.7.5 isn't really better.

• OS X El Capitan - Technical Specifications

• Upgrade to OS X El Capitan - Apple Support

The machines ^ listed (hardware dependent) are capable of upgrade to the new OS X.

If you identify your computer exactingly, the details may show important information...

• Identify the model of your iMac - Apple Support

• Apple iMac Specifications (All iMac Specs - all year versions)

http://www.everymac.com/systems/apple/imac/index-imac.html

• Actual maximum RAM of all early G3 through Later Macs:

http://www.everymac.com/actual-maximum-mac-ram/

Older Macs that can run OS X 10.11 may have limits to some aspects of the system

that will not be supported in the non-upgradeable hardware. You can add RAM memory

and a larger capacity hard drive (or faster spin rate, to include a solid-state-drive) to

help an older supported machine work quicker with a newer larger system.

An example of reputable supplier of upgrade & replacement parts for Macs:

http://eshop.macsales.com/MyOWC/

Good luck & happy computing!

In addition to the excellent replies you've already got, let me just add that even if it says 2GB minimum, to get really any decent performance you need at least 4GB (8GB if possible); and if you really want to get a new lease on life for your older mac, put an SSD on it. You'll be amazed at how much faster it becomes. It is like having a new computer for $200 or so with the RAM and SSD.

the 2GB RAM statement from Apple in theory may work for Apple but from posts on these forums you begin to see it was enough to use that OS where it is not spending most of it's time reading and writing to your Hard Drive (intergalactically slower than using available RAM), the result is an OS is highly unresponsive and delayed because it's struggling to do the simplest of tasks.

2GB RAM is enough to boot to the OS, but once you start trying to use applications you will instantly notice a performance drop for everything.

Even users with 4GB RAM can have significant issues with 10.11 especially when they begin to try and multi-task.

10.11 is a good OS but it's optimal environment begins with computers that have 6 to 8 GB RAM otherwise it may be a undesirable update decision.

Either way back up with time machine before you proceed as it's difficult to go back if you update and find you hate it without the backup to turn the ship around.

Use Time Machine to back up or restore your Mac - Apple Support

Although you've appeared to have read through this thread, unless or until you

can look into the About This Mac from the Finder, and click the button "More info"

so the system profile for hardware appears, and you can see the Model Identifier

number, you're no closer identifying correct parts to upgrade the hardware either.

Could be that your iMac model, if it has an early Core Intel processor, may be

near the highest OS X it can run. The Model Identifier can help determine the

age and hardware version of the computer in question. If the computer is not

of the Core2Duo or later CPU, the unit cannot run El Capitan. Some can't go

much further than Lion 10.7.5. (Identify the computer, for detailed replies.)

While I have access to in-computer and online resources, and spend a fair bit of

my 'free' time each day on reading through to help resolve a few issues people

may have, or to confirm web page URLs to specific information to add to replies

most of the answers to your problem for the most part, are in the computer itself.

What happened to the MacBook computer you had some time ago, and posted

inquiry in another ASC discussion about it? Was it repaired or replaced? IF the

computer in this thread is not an iMac, that also could change the advice given.

Anyway, I'm looking at 1:30PM local time and am going offline. As helpers here

are for the most part fellow Apple users like you, the peer-to-peer volunteers

are not compensated, and can only do so much with so little information.

In any event...

Good luck & happy computing!