A PC doesn't draw nearly the amps an AC compressor does (unless you are gaming w/SLI rig). I can see my lights dim when my compressor kicks on and my 120 volts can drop down to 116. So even if your on a "unstressed" outlet, it could be something on the same circuit.
My outlet (note, this actually only plugs into one of the two hardwired outlet plugs):
Top Left (big fucking cable): PC*
Middle Left: Up Tech - "The Core"
Bottom Left: Monitor 1
Top Right: Monitor 2
Middle Right: E-nano
Bottom Right: Halogen floor lamp
*SLI gaming rig you say?
Note the
1200 Watt power supply at the bottom, and the insanely power hungry**
SLI GTX-480s graphic cards.
**
BTW, everything from the cards to the CPU to the RAM is overclocked in that rig... meaning its drawing considerably more power than the same equipment at standard speeds. It also has 10+ fans, and a liquid cooling system running 24/7.
In any case, I've been running things like this for the better part of a year, and you better believe I vape the shit out of stuff when I'm gaming... at night... with that lamp on.
...and yes, I can heat a North Korean village with this thing. My office gets pretty damn hot even with the central AC on if I'm stressing those GPUs. I've seen each chip top out at over 90°C. Id change them out for something more efficient, cooler, quieter and faster... but I'm waiting for one of these to die (going on 3 years now) or a game to come along that I cant max out with playable framerates. Maybe when the 980 is released...