Damn hvor folk blander hz (opdateringsfrekvens) og fps (billeder pr sekund) sammen.
Edit:
FPS vs. Refresh Rate
FPS and refresh rate are two separate things. Even if the image on your screen has not changed in any way (e.g. a still 2D image like your Windows Desktop), or your 3D game isn’t actually supplying enough new frames (e.g. the game is running at 25 FPS on a 60Hz refresh rate), the screen can still be redrawn a fixed number of times based on the current refresh rate of the monitor; if your FPS is less than your refresh rate at any time, the same frame may simply be redrawn several times by the monitor.
If your FPS is higher than your refresh rate at any time, your monitor will not actually be able to display all of these frames, and some will come out with a graphical glitch known as Tearing. To prevent this, you can enable an option called Vertical Synchronization (VSync). However here’s the tricky part: if VSync is enabled, then your refresh rate and FPS will have a direct relationship with each other – they will become synchronized together. This is all covered in more detail in the Vertical Synchronization section of this guide.
Klippet fra http://www.tweakguides.com/Graphics_7.html
Edit2: Dvs at hvis du har et spil med 30fps, så bliver den samme éne frame vist 2 gange på en 60hz monitor, mens den bliver vist 4 gange på en 120hz, da den opdaterer dobbelt så hurtigt…