Could be power.

Many PCs ship with under sized power supplies.  Add a video capture, a
decent non-UM video, second hard drive and you could be pushing the
limits.

Alternatively, load Linux in dual boot, if you have the problem with
Linux, it is certainly hardware.

If the computer is doing a soft reboot (versus shutting off completely),
then
you can configure it to display a blue screen rather than automatically
reboot. A stop code should be displayed (e.g. 0x000000A), along with
a related identifier, like IRQL_NOT_LESS_OR_EQUAL.

The first step then is to configure your Startup and Recovery settings.

1) Launch Start -> Control Panel -> System.
2) In the Tasks pane, select 'Advanced system settings'.
3) On the System Properties dialog, click the 'Advanced' tab.
4) Under 'Startup and Recovery', click the 'Settings' button.
5) Under 'System failure', uncheck the 'Automatically restart' button.
6) Click OK on both dialogs to exit.

Now the next time the computer has an error reboot, you should be
presented with a blue screen and error code. Write down the error
code and perform a search online (and/or post the code back in this
thread).

The most typical cause of this type of error is a driver error, though it
could be faulty hardware or improperly seated hardware components.

Cheers,
Garrett McGowan [MSFT Developer International]

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