Chosen Solution
Our Mac Pro 5 powers up, but will not load the operating system. It gets stuck on the grey screen with Apple logo, and appears to be loading. After a few minutes it powers off, and re0boots, continuing this pattern until i manually hold the power button down to power off. Please help!
Your hard drive may be fouled up, or your OS is severely corrupted. Try booting into safe mode by holding the Shift key as soon as you boot up. If you are able to Boot properly in safe mode, check your Hard Drive using disk utility and make repairs if necessary and immediately reboot. This failing, get back to us.
install another harddisk and put a fresh osx install on it. Then migrate your data. that if it’s the harddisk.
