dell offers a full 1 year warranty at least on a monitor so returning it to them if faulty is the best option here,
That warranty would cover repairs not to return the monitor for a refund. Dell is not near as generous as Apple when it comes to returns.
Several days have passed since I reset to factory settings on the Dell monitor and it hasn't blinked once. So I guess there was some setting I tweaked that it didn't like. Problem solved. Thanks for all the input. I appreciate the responses.
If you want to get the monitor temp to match your iMacs monitor temp here's something to try. I don't think it will mess up what you've done to get the monitor working. It doesn't change the timing (which I suspect is the cause of the issue):
Several days have passed since I reset to factory settings on the Dell monitor and it hasn't blinked once. So I guess there was some setting I tweaked that it didn't like. Problem solved. Thanks for all the input. I appreciate the responses.