Turn off by itself, then won't turn on without sitting for a while.

The diagnostic LEDs to the right of the RAM slots (this may be covered by a piece of black electrical tape).

ED Startup Sequence

LED #1 = Power available.

If no LED is visible:

• Verify AC source

• Verify known-good AC cable is connected

• Verify cable connection between AC inlet and power supply

• Verify cable connection between power supply and logic board

• Verify power supply

LED #1 + LED #2 = Power available, and system is powered on.

If second LED is not visible when power button is pressed:

• Verify power button connection to logic board

• Verify power button functionality

• Verify cable connection between power supply and logic board

• Verify power supply

• Verify logic board

LED #1 + LED #2 + LED #3 = Power available, system is powered on, and video card found.

If third LED is not visible after power on:

• Verify that MXM video card is seated properly

• Verify logic board

When it shuts down pay attention to the diagnostic LEDs and the flow chart I posted in this thread. When it powers down if the first LED goes out it is a power supply problem. If the first light remains lit it is either something over heating or a memory issue. Please let us know what the LEDs are doing.