XPS L702X Freeze/hang using Intel HD 3000 with Balance Power plan

Specs:

XPS L702X

BIOS: A19

CPU: I7-2630QM

RAM: Hynix 2x4G 2Rx8 pc3-10600s-9-10-f2

Video: Intel HD 3000 / Nvidia GT555m

Hard Drive:  Western Digital 750 GB

Optical Drive: Blue-Ray

Background:

I bought this laptop second hand.  When i was checking it out with the seller, it worked fine for the few minutes we met.  Later that evening, when i had more time to use it, it would crash randomly.  I guessed that it was an overheating issue especially after remembering that some of the pics of the laptop in the ad had it sitting on an aftermarket cooler.

The crash would appear as a screen freeze / hang.  However, the mouse pointer would disappear a second or two later.  Because the screen would update, it wasn't a total video lock up.  Occasionally, i could hear the fan speed up shortly afterwards.  Whenever i crashed it required a hard reboot by holding down the power button.

I took the laptop apart.  It was apparent that it had been taken apart before as some screws were missing and some had marks from a screwdriver being used on them.  The inside of the laptop was very clean including the fins on the heat sink.  The CPU and GPU had generous amounts of thermal paste.  Some of it had spread to the surrounding diodes.  I cleaned them, properly applied new paste (Prolimatech PK1), and put the laptop back together.  It still crashed.

The previous owner had Windows 7 on it, but it was apparent that it wasn't OEM or at least highly modified.  I restored Windows 7 from the Dell image on the hard drive.  I then updated all the drivers from the web site.   The computer crashed.

There were a couple things i could do and it would not crash.  If i went into Device Manager and disabled the Intel HD 3000 video card, i could reboot and it would use the Nvidia card.  The resolution was reduced, but it was stable.  I installed most drivers this way.  Also, if i booted into Safe Mode the computer seemed more stable.

I installed a few temperature monitoring programs, but they seemed normal (high 40c to 70c ever so briefly).

I ran Dell's BIOS level diagnostics and it passed even the long memory test.  If i ran Dell's PC Checkup program and did a test of the Intel HD 3000, it would crash every time at random points.

The BIOS looked recently updated.  It had version A19 on it, and the service tag was missing which i put back in.

Solution:

While i comtemplated which hardware component was to blame, i started taking another look at the installed drivers and programs.  This led me to Dell's Quickset program.  One of the functions is changing the power plans.  While i could have changed it within Quickset to the same effect, i went ahead and changed it in Windows Power Management instead.  I chose High Performance.  The laptop now doesn't crash and will run PC Checkup's Short and Stress tests on the Intel HD 3000 all day long.  If i put it on Balanced, it crashes again.

Resolution:

Running a High Performance power plan works, but i don't consider the problem resolved.  I also am searching for ways to find the "real culprit".  The Intel HD 3000 uses RAM for video memory.  I'm not sure if the A19 BIOS update doesn't supply enough power to the CPU or RAM.  I may try re-flashing to an earlier BIOS. I also suppose that it might not be getting enough power via the mainboard.  I may look for 3rd party software that will give me the voltage information.  The RAM tests out fine in the BIOS tests and Dell's PC Checkup program (HiPer power plan active).  There's also many other components affected by the power plan such as wifi, display, USB, etc.  Any of them could be the culprit.

Any suggestions on how to track it down?