A client brought me a VPCF136FX laptop for some software maintenance and when I got it I realized the fan was a little noisy so I ordered a new one and continued working on it. Shortly thereafter the video began failing so I took it to a hardware tech I know to check it out. He told me the soldering near the GPU had cracked from heat (presumably from the failing fan) and he was unable to repair it. The client purchased a new unit and I put it her old one in my strip and recycle pile. I dug it out yesterday and out of curiousity hooked it up to an external monitor and it worked fine, though the video on the on-board monitor was as before, with "static" on the screen and on-and off display. At boot time the VAIO logo appears for less than a second and then disappears. If I boot with an unformatted hard disk in place I get a test warning about no operating system, and while the text is readable there is random visual noise on the screen.
My question is, is there a separate GPU for the on-board and external displays, or is it all handled by one GPU? I've removed the on-board screen and plan to use the unit with an external display only, and would like to sell the screen on Ebay, but don't want to if the problem is in fact with the screen itself. I have a call into the tech who worked on it, but he is bad about returning calls and the question may be above his pay grade anyway, so I thought I'd ask it here. Thanks for your help.