Well done @dosdude1 ! So the 603 GPUs are fairly distinct at a glance with the outlined NVIDIA logo instead of being solid white on the 602. What are the typical symptoms of a failed GPU? Reason I ask is I have a few more units with the 8600M GT. One of them just powers off when the power light and fans come on. DC-in charged up the battery OK. Another unit clearly has GPU failure with purple and red artefacts covering the display during boot, then kernel panics after the GPU kext loads. It will boot in safe mode with it's glitchy graphics.