sounds like your psu may be starting to fail. if you still have some warranty on the machine i would contact dell and let them know about it so they can send you out a replacement psu.

The PSU could go at anytime or it could last you for years. If the PSU fails it may or may not do damage to your other components within the system depending on how it fails. If it were my PSU I would be buying a new one and replacing it asap because I wouldn't want to take the chance of it failing and maybe even taking out other components within my system such as the motherboard, processor or video cards.

Warranty is past so I will need to pay for it myself.  I also wouldn't want to replace it myself...

Any idea how long my PSU has to live?  approx ofc :P

What happens if it does fail, will it affect the rest of the machine?  It only happens when I've been gaming for a while, so I don't know how serious it is.

Thanks for the reply.

Replacing the PSU in the Aurora is a snap.  They are expensive from Dell, but you can find the smaller unit (525W) on ebay for around $100.  If you need or want the 875W unit, Dell is pretty much the only place I've found to get it.  You only have to pop off the side access cover, unplug the computer, loosen four screws at the back, and unplug a single modular connector on the PSU.  Remove the unit and unscrew the four mounting screws that hold the plastic mount on the PSU.  Reverse the process and your done!  There are several videos on youtube showing the process.