Problem with ports and mac pro 2013 turning off randomly

Hi all,

Just a quick one to see if anyone has any advice on this or has experience anything similar. I'm on a late 2013 Mac pro (3.5 6 core) Cylinder running 10.13.3.

A few weeks ago my mac started displaying some sister behaviours. Crashing if a monitor was unplugged or turned off was the most common. Normally when this happened, after I restarted the machine, it would be so slow that it was basically unusable, like it would take 5 mins for the mouse to move across the screen, keyboard wouldn't work, and sometimes the computer wouldn't recognise the USB ports or monitors. The trouble with this problem is that when it occurs, I can't do any startup commands e.g. starting in safe mode, recovery mode etc, because it doesn't seem to recognise the ports properly, especially the USB. I've tried plugging monitors, keyboard, mouse into different ports and isolating buses but it doesn't make a difference.

Now my computer is also randomly switching off, and sometimes takes about 30 mins of continual restarting to get it to turn on and work normally. It appears to be random when it does work.

I've tried hardware tests, reinstalling operating system, resetting SMC, PRAM etc, and nothing seems to work. I've run a diagnostic which didn't show anything, and have done a disk check which was fine. The RAM is also showing is fine in the system report.

Seems like a hardware problem but I'm not in a work schedule position at the moment to have the computer repaired. Any ideas?

Thanks!