Vaio FW GPU Voltage Bump?

Model: FW490JEB
GPU: ATI Mobility Radeon HD 4650 1GB DDR3

Well, I'm 99% certain the reason why my system freezes (Black screen, or corruption) during intense load is because the GPU is simply not getting enough voltage, even with stock frequency. Now, other laptops have this particular GPU, and they run slightly higher, so my question is, is there any way that I could change the voltage slightly higher? Like perhaps flash a new bios? I have checked my temperatures and I'm not exceeding anything, infact I've run the computer with an AC blasting the bottom of it and it still did it. Running latest available driver, and I have also tried the stock Sony driver as well.

Current available voltages:
Idle: 0.9V
Load: 1.0V

I'm thinking 1.05V-1.15V

Any ideas?
Thanks

Edit: I should also mention this laptop has been in for service 5 times since SONY Repair are completely incompetent. Replacements: Motherboard, keyboard, fan (x3), DC Power in Jack, mouse trackpad, palmrest. The new motherboard made the laptop a bit more stable.

 

Could you detail the troubleshooting steps that led to this conclusion? I have to say it seems extremely unlikely.

 

I would think so too, considering Sony should know what they are doing.

1) The laptop gets video corruption even when the temperature is too low to signal thermal shutdown

2) The laptop stays on longer when I force it to use 1.0V rather than 0.9V

Plus I haven't even started to overclock the GPU, which I very much would like to. Considering the GPU was underclock by Sony to begin with, I'm certain higher voltage and frequency won't hurt it.

I mean really, What else could it be? When this happens, stuff like music keeps going in the background so I know it's not say the CPU or RAM.

Things that shut it down: Crysis (Random amount of time), Prime95+FurMark

 

Definitely sounds like it's related to the GPU, but if it was underclocked by Sony then they will have had a reason for it, probably thermal.

When you say they've replaced the motherboard, do you know if that included the GPU or not? I'm not sure how discrete the 'discrete' graphics is on that computer, and you didn't explicitly state whether they'd replaced the GPU itself.

 

Yeah, the motherboard replacement included the GPU. I really don't know why Sony underclocked it, but people on this forum have easily clocked it back up, so it's doable. I just want to know thought if I can bump the voltage up. I opened my laptop today and replaced all the thermal paste with high quality Arctic Silver Ceramique and that has dropped my temps all around by at least 5C,and 10C on the CPU.

 

So, does anyone have any ideas?