Dell XPS 720 Tripping Breaker

Hi guys, I have had a Dell XPS 720 roughly two years, (before I learned about building and what not, building a new rig in a few days to replace the dell).

My problem is that sporadically my computer will trip the breaker, sometimes it occurs while the system is on seemingly at random. It is a rare occurance, it happened at load, and at idle.

Most recently, and this scared me enough not to use it anymore. I hit the power button, and everything in my house went off, and came back on.

I believe the culprit is more than likely the power supply unit, however, I had a local PC repair shop take a look at the PSU and they said it was fine. I imagine he just checked the voltages, and it does power on the system, I'm just suffering from occasional power outages.

Also, it's a 750watt supply, with a 24pin and 20pin connections to the motherboard, so BTX. Would it be worthwhile to replace the PSU? Or could it be another component?

At the time of these outages the breaker should not have been stressed, only the computer and monitor were plugged into that circuit and on.

Thanks very much for your help!

(originally had this in the Dell sub-category, but deleted it there and moved it here)

Why don't you get a power protection device. Newegg sells several, including some that have battery backup if you have frequent power outages.

That doesn't make it BTX, just Dell proprietary.