Another thing I've found since I've transitioned to using TVs as monitors: the "PC Mode" can still have really bad picture quality. Now, with that said, let me elaborate a little further - depending on the manufacturer and model, the "PC Mode" setting can do anything from 1.) simply change the color "temperature" to a cooler setting (a cool or blue push to the whites); 2.) change the acceptable RGB range from limited (15-235) to full (0-255); or 3.) some crazy combination of 1/2 to anything in between and then some.
Generally what I do is to hook up the TV to a Blu-ray player and load up the free BT.709 calibration disc you can download from www.avsforum.com
and dial in the basics like brightness, contrast, and color. Then, I manually disable each of the "image processing" settings in the TV's software menu (e.g, turn off the backlight dimming/ambient light sensor; turn off any "digital clean view" and "MPEG noise reduction"; make sure it's set to 1:1 pixel mapping to eliminate any overscan; etc.). On Vizio TVs, for example, I find the "normal" color temperature to be the most accurate AND the most pleasing/natural looking (Vizio's "PC Mode" temperature has a horrible blue push that will make you think of an Arctic glacier under a clear sky). For Samsung TVs, most review sites recommend the "Warm 2" color setting/temperature, as for whatever reason, this setting on Samsungs will generally get you close to the D65 white point that modern displays are calibrated for.
So, short story long, do yourself a favor and play around with the settings. Don't just kick the TV into "PC Mode" and assume you are getting the best and/or most accurate settings. I stress that my experience is biased towards Vizio TVs (I have 3 that I use for monitors), and each manufacturer's settings are different and do different things.