Hey Stile5240, Regarding the defective M90 GPU, l’ve had several M90s and the GPU is very much replaceable. You seem pretty certain about the GPU, thus l hope you take no offense, However if you can provide some more info perhaps someone here can help you definitively identify that the problem is a defective GPU.
M90 GPU options*nVIDIA Quadro FX 3500M
nVIDIA Quadro FX 2500M
nVIDIA Quadro FX 1500M
*The M90 shares the same form factor and/or power requirements with several...