The upper bound is just dictated by the quality of the RAMDAC of your graphics adapter. There's unconfirmed legend of some consumer gpu once supporting 500MHz (even though that may have originated from a Windows control panel bug) but in the professional space or with some adapters even 550MHz is not unheard of. The NEWlink VGA to HDMI converter can convert the analogue signal coming from your PC into a digital HDMI signal. This allows you to plug your older laptop or desktop computer into a modern HD television. Nothing is infinite, and so both VGA and HDMI will hit a wall sooner or later. But the limit is going to be bandwidth, not resolution (or frequency) per se. VGA input format: 800x600 / 1024x768 / 1280x720 / 1280x768 / 1280x800 / 1280x1024 /1360x768 / 1600x1200 / 1920x1080P @ 60Hz