is my 27" iMac 2017 model, w/intel failing?

ronline1111 wrote:

still nothing until I unplugged the power, waited 10 mins and tried again. This time it booted up (slowly) and was working ok for a couple minutes then the screen started flashing (mostly blue) and went back to the sign in screen.

That is indicative of a failing power supply. You might take it in to the nearest Apple Genius Bar for a free evaluation. Apple won't be able to repair it as it's considered Vintage but they will test it for free. You'd have to take to an Apple Authorized Service Provider for service.  A power supply should not cost a lot, certainly less than a new Mac.

If you are leaning towards a new Mac consider a Mac Mini with a 3rd party 27" 4K monitor w/speakers. That combination will cost up to $500 less than a comparatively configured 24" iMac.

Just some food for thought.

Yes, I think it's time for a new Mac.

You are getting unpredictable hardware problems and the cost of repair is likely to exceed the cost of a new iMac. Plus your 2017 model is well into the 'obsolete' category.

Yes, I agree with MartinR and what he posted/wrote… your external drive may be fine, but the rest of your 27” iMac? No, not good, and to repair it would cost more than buying an Apple certified refurbished or new iMac… I presume you’ve already done and are doing regular backups… if so, time to think about recycling it and going for one of the 2 options i mentioned… or a Mac mini plus cd/dvd drive+ monitor, keyboard, etc …

John B