Chosen Solution
Some times it runs for long periods of time but then when I try to work on it well it shuts down, or the screen goes black. Doesn’t seem like the machine actually shuts down just the screen? I’m thinking I need to reseat the graphics cards with some fresh arctic silver paste?
You’ll need to see if you can access your system from a second Mac using screen sharing when you loose the display. Are you abel to get to it? If you can’t you’ll need to run diagnostics holding the D key when your restart the system. Then check the onboard diagnostic LED’s reference: Mac startup key combinations I wouldn’t refresh the thermal paste quite yet.
