IAs you need an older MacOS version probably is not available from the Apple store so you need to get it from a third party.
All older OSes are available from Apple.
It's not a Mac book, it's a Mac Pro as I said in the original post, but thanks for the response anyway.If the fault shows on battery power just the same as on mains theres a fair chance you could discount both as the cause , 2012 laptop battery must have been replaced by now
Re-doing the heat-sink compound on the processor/graphics might be another thing worth considering . Ive virtually no experience with Macs , but I do have a Lenovo thinkpad T61 that had a very similar fault to what you describe , once I re-seated the heatsink/compound she's worked flawlessly ever since and I still run a 32bit os on it so I can connect via Usb to my Akai DPS24 for file transfers.
Thanks for this info. Unfortunately where I use it there is no internet so loading programs is a right pita, but I will see what I can do about loading macs fan control.I use a 2009 Cheesegrater, upgraded to 2012 spec..
Could be a problem with local overheating. You can check this with most temperature monitoring software.
I use Macs Fan Control by Cryastalidea. Free version will do.
Look at Northbridge Diode (75-85°C is fine) or Northbridge Heatsink temps (65-75).
The heatsink on that chip is fixed with plastic push-pins, so thermal contact between chip and heatsink gets worse over time.
The rising temp doesn't cause the fans to speed up, it simply triggers a shutdown/reboot.
Thanks for the response. I have already worked out I need yosemite for PT11.I run a Mid 2012 13inch Macbook Pro, I used it everyday in the last 10 years it's a great machine.
I never had the problem you describe but the first thing I would do if to format the system hardrive and do a fresh MacOS install.
I'm on Pro Tools 10 so I use 10.9.5 Mavericks on my machine, you have PT11 so just download from the web the last OS that works well with PT11. You can find the download links for the different OS in Torrent sites, if you need help for that send me a PM. As you need an older MacOS version probably is not available from the Apple store so you need to get it from a third party.
So do a fresh install and see if that solves it.
I hope it will because once you use a MAC you are not ever going back to a PC, I was a PC/Windows user for 22 years until I got my first Macbook and couldn't believe how simple life could be.
Thanks for the response. I have already worked out I need yosemite for PT11.
To be honest I have always found macs to be problematic compared to pc's (don't shoot me). This is the third one I have had so I'm not without experience with them.
If you need a copy of snow leopard I might have one on cd/dvd somewhere.
I can't get Mavericks, Mountain Lion, Lion, or Snow Leopard from the app store.
I don't know about other older versions but at least these ones are not available any longer from Apple, you can still get the original releases from other sources
Thanks for the tip.I have PT11 working with mojave on an 2012 Mac pro. I used PT 11 with High Sierra for a few years with no problems. If you get it running maybe try it with high sierra on a new hard drive. I do recommend keeping your old os and switching the startup disk.