Dell XPS M1710 Modification problems

I have a xps m1710 that I use as my mobile machine booted with windows 8.1 I've upgraded most of the upgradable parts of it. I swapped out The old 9700gtx that had failed and put in a quadrophonic 3600m, the machine does work with the 3600m but the brightness on the screen does not work so it appears at the lowest brightness setting. I Swapped out the stock wireless card and put in a card that supports 802.11n put a 750Gig hdd into it and put 4 gigs of ram into it leaving the stock 2.16 ghz cpu.
The only thing problems that the machine is having are with the display, recently I was stress testing the machine and the GPU hit about 90 degrees and the screen started bugging out Then started flashing 5 colors Changing every 2 seconds( white black red green blue), I assume to stop the GPU from rendering anything to let it cool down. I let it cool down and the machine returned to normal without restarting it. After a second stress test it got up to 90~ degrees again and started flashing the colors So I restarted the machine But it is still stuck in the 5 color patern and does not display anything else. I plugged it into a external monitor and the machine operates just fine. The only other problem is that the brightness on the built in lad is stuck at the lowest value but the main problem is the lcd not displaying anything else other than the 5 colors.
Anyone got any ideas on what's wrong?

 

I'm moving this thread to our Hardware forum where I think you'll have a better chance of getting replies.

Charles