UPDATE from the apple store
... So today I took my macbook apart. Removed the logic board,cleaned off all the thermal compound off the heat sinks and the cpu , gpu and nvidea chips..My computer is 8 years old keep in mine and it was very clean in the inside..I then used my heatgun to heat up the nvidea chip and around the chip for about 40 seconds(heat gun goes up to 1000 watts.,had it turned down half way). after a couple of rounds of heating. I cooled it off then applied Artic Silver 5 thermal compound to the heat sinks and chips using very little,very thin.(too much caused overheating) just enought to cover the surface area's..I reassembled the Mac and started it up..Everything works..I then did the hardware test again..It came up with "NO TROUBLE FOUND"....Hopefully this will last.Maybe all that was needed was to replace the thermal compound that was on there.After all it was all dried up and flaking..Good luck guys...