You're running a XP-M2400 at 2.1v (207*13). Hmmm... I use a lot less than that with a 2600M, but I'm at much lower voltage and only 200x12.5. I'd tend to trust my own measurements over a script.
You can get a kill-a-watt for under $30 (here's a
froogle search). You plug this into the wall, your PC into it - and it reads out the wattage you're using. If you're married you can easily justify this thing to your spouse as "something to save electricity"
Your power supply is 80% efficient if it's a Seasonic, otherwise, it's probably more like 70 or 75 (if you've got the docs from your ps look there). PS efficiency changes based on how many amps you're pulling, so this is kind of a guess as well
So...try starting your PC with as little in it connected as possible. If you've got a "cheapie" video card, try using that - the difference between with the cheapie and with your gaming card is pretty much the wattage your gaming card uses.
You get the idea. FWIW, these are pretty decent little devices - recently had a conversation with my brother in law, who runs (among other things) the lab the readings for those yellow stickers you see on appliances come from - and
he says they're pretty good.