Optiplex 7010 Screen flickers

We have a  Optiplex 7010, all parts are stock, we are getting flickering screen so bad (unusable/cant see anything just like garbled color bars), sometimes works for 15 mins but it wont last for continuous usage.Checked BIOS status, notice CPU temp is maxed, i tried reinstalling Windows, even tried Linux still getting the same. Can you please advise me which hardware component is failing, is it video chip or the processor?

Thanks

Jorge