My 27" iMac - Fuzzy area on monitor

You can mitigate some basic heat issues to see if the spot goes away:

---Make certain nothing is between your desk and the botom of the case. Stuff placed under the computer will block important air intakes.

---If the bottom of the case has a lot of dust/lint/cruc stuck to it vacuum it off. Try not to touch the case with the vacuum nozzle.

---Make certain nothing is obstructing the long slot at the top of the case back. This is the exhaust port; placing the computer too close to the wall behind it or having papers hanging over the slot will trap hot air inside the computer.

---Get a temp monitoring utility. I like this one:

http://www.bresink.com/osx/TemperatureMonitor.html

because it puts the temp display in your menubar.

I have a 27-inch 2010 iMac and it's been running Safari with multiple tabs open for a couple of hours straight. No single component is hotter than 135F/57C (secondary heatsink). That is a normal temp for that component.

If you have AppleCare extended waranty coverage, don't worry about doing anything yourself--take it to an Apple Store right away for diagnosis.

This may or may not be applicable: http://support.apple.com/kb/TS5167

That's sounding good. Mine has been idling for about 45 minutes while I had lunch and the graphics processor diode is currently at 127F, so your number sounds reasonable.

Did you get SMC Fan Control? I have it installed. Most of the time I have the default Apple speeds set, about 940 rpm on the CPU. If I start something that I know will elevate temps (videos or a game), I have a setting saved as "Higher Load" that sets the CPU fan up to about 1250 rpm--still plenty quiet.

If I run Windows 7 via BootCamp, I have a setting for that with the CPU fan at about 1500 rpm. It turns out that, if I set the speed up before booting into Win, the fan speed stays at the higher level while running Windows.

Another strategy I have in play is an old dual-sensor digital thermometer that has a remote sensor intended to measure outdoor temps. The main unit sits on the "foot" of my iMac, measuring temps where air is drawn it. I have the remote end stuck in the exhaust slot. As we don't have the same temp reading software for Mac as Windows, the remote sensor measures something that's the same regardless of which OS I run.

Exhaust air temps are about 5-10F higher running Win 7/64 Home Premium than when running MacOS 10.6.8