I have heard of people putting in a 27' video card but you'll need to swap out the heat sinks as they are different. Ati radeon hd 5670 driver for mac. The best the 27' model had was the ATI Radeon HD 5750 (1 GB) Apple P/N 661-5579.But given the fact you only have an i5 you may want to look at getting a used 27' i7 system with the better GPU than trying to upgrade this one. Sorry for coming late to the party here;-The best this system came with was a ATI Radeon HD 5670 (512MB) Apple P/N 661-5546. Gaming really needs the bigger display and the more powerful CPU.Just be careful here!

It is rare but your Mac can freeze and become unresponsive. While the macOS Mojave update brings a lot of great features, users are reporting number of issues, such as the battery drain problem. One other problem that’s affecting many Mac users is the entire computer freezing when attempting to login. Are you having freezing issues too during or after login. Is your Mac unresponsive and misbehaving? This article explains what you can do to fix this problem. These tips may help you resolve your issue.

Download catmaker for mac. Which Mac apps will stop working. The problem of Catalina incompatibility is not only about third-party apps. Apple is not 100% prepared too. For people working with multimedia projects, it’s important to know which Adobe software won’t be working after the update. So take a deep breath, and see what’s going away.

Try backing up your Mac before trying the tips below.

1. If your Mac freezes after you login, some single app may be causing the problem. Simply press the Command+Option+Escape keys together (or click Force Quit from the Apple menu). Force Quit Applications menu will appear. Select the unresponsive app or apps and then click Force Quit.
2. Start up your Mac in safe mode. This is one of the most common steps when troubleshooting your Mac. If your Mac is not starting normally, safe mode is the next step you should try to troubleshoot. To start your Mac in safe mode, follow the instructions below:
   1. Turn off your Mac
   2. Turn on your computer and immediately after (immediately after you hear the start up sound) the computer is powered on, press and hold the Shift key.
   3. Release the Shift key when you see the login screen
   4. If your computer does not freeze in safe mode, restart your Mac normally, without pressing the Shift key.
3. If safe mode does not help you, you may try macOS recovery. Here is how:
   1. Turn off your Mac
   2. Turn on your Mac and immediately after press and hold the Command – R keys together. Keep holding the keys until you see the Apple logo. Release the keys when you see the Apple logo.
   3. You will see the macOS utilities window
   4. Select Disk Utility and click Continue
   5. Select View > Show All Devices
   6. Select your start up disk
   7. Then click the First Aid button and then click Run
   8. Then restart your Mac normally by choosing Restart from the Apple meu.
4. If you are still having your problem, reinstall macOS. Here is how:
   1. Turn off your Mac
   2. Turn on your Mac and immediately after press and hold the Command and R keys together until you see the Apple logo.
   3. macOS Utilities window will appear
   4. Select Reinstall macOS and follow the instructions.

See also: Mac White Screen