 320×200 @ 70 Hz is the most common mode for VGA-era PC games, using exactly the same timings as the 640×400 mode, but halving the pixel rate (and, in 256-color mode, doubling the bit-depth of each pixel) and displaying each line of pixels twice.The actual timings vary slightly from the defined standard.For example, for 640×480 @ 60 Hz, a 25.17 µs active video time with a pixel frequency of 25.175 MHz gives 634 pixels, rather than the expected 640.