Desktop Boot and Lockup

A month ago I bought a brand new Envy Pavilion TE01-1134 desktop PC from Best Buy. I LOVE all the features, but it froze several times a day at random, even when I was logged off. The clock stopped, and only turning it off and on again got it going again. Error logs for the time that it froze showed nothing. The PC wasn't near anything that could block the fans and wasn't near a heating vent.

I updated all drivers and the BIOS, and ran every diagnostic for the system software and hardware. No errors.

The only time it DIDN'T freeze was when I ran the UEF1 diagnostics for 48 hours from bootup <esc><F2>, continuously in "run until error" mode. No problems.

I used every restore point, I re-installed Windows using every option in Settings and using the F11 option on bootup. I created a new Microsoft account, and initialized a complete factory Windows re-install with the minimum necessary to get it running.  In every case, it still froze in anywhere from 15 minutes to 15 hours. I finally concluded that it must be a defective unit and returned and replaced it.

And the new unit ALSO freezes, with the only additional programs installed being Google Chrome and Google Drive. I'm at my limit for what to try. Is there a chance that upgrading the graphics with a larger power supply and separate board instead of the integrated graphics might solve the problem?