Constant Crashing

Are you seeing kernel panics? If so, get one and post the text here.

Mac OS X: How to log a kernel panic - Apple Support

Otherwise note the EXACT time when this happens: hour, minute, second.

Use Console.app to examine the logs for that time, and post at most one page of log entries for readers to look through for you.

When the new crash occurs note the exact time. Ther upon reboot open the COnsole app in Finder>Applications>Utilities and look fort log entries at the time. Post suspicious ones here.

If you get a kernal panice log it and post it here:

Mac OS X: How to log a kernel panic - Apple Support

Does it happen when you disconnect all peripherals except mouse, KB and monitor?

Run Apple Hardware test

Using Apple Hardware Test

I to had graphics problemhas been detected with earlier versions of Yosemite but those have now stopped

Have you followed suggestions? Mine would be a clean install on freshly erased drive, don't install or use Chrome for awhile and see how it goes.

The time to address this was month(s) ago when it first happened and when you had a good stable system image backup/clone that you could use to restore from, and start investigating and troubleshooting then (Safe Boot, Recovery Mode, Etrecheck, etc) and good use of Carbon Copy Cloner and a clean install.

It is nice of you to think about the whole picture for all Users, but Apple is a BIG company, and there is no obvious place to send those reports unless you have access to Developer Tech Support, National Account Support, or Education Support representatives.

The alternative for everyone else is to think about yourself, not everybody, and take your computer and your printed logs to the genius bar of an Apple-owned store (if you have an appointment, evaluation is free), or contact telephone support if you still have coverage (otherwise there may be a fee).

Anything that can be reproduced can be fixed. It may not be fixed in the most clever way you could imagine, but they will provide service part replacements until the problems go away, or escalate unsolvable problems from there into Engineering.

What they will NOT do is provide support for third-party Hardware or Software. So you need to be running a system free of third-party kernel extensions, and no third-party anti-Virus. They are also likely to ask you early on to do a clean Install onto a blank drive.

My point is if you think you are out of the woods, grab CCC and use it, and if you are not yet, do a clean install and image that while stable just in case you want to.

You might have had a clone or restore image or had ability and even tried using TimeMachine, no need for a phone booth, and just not mentioned in your posts. We don't know.

Like buying insurance after the car is totaled? Or buying power backup after the storm, better prepared next time.