Talk:Problem with DVI throughput

Here's some information I found:

Most DVI devices today use single-link DVI which supports a maximum bandwidth of 165 MHz [1]. I suppose that ThinkPads provide a single-link DVI signal.

To calculate the bandwidth of your signal, in theory you just need to multiply the resolution with the vertical frequency. For example: 1600x1200 @ 85 Hz => 1600*1200*85 Hz = 163 MHz. This looks good, but it is outside the specs - because you need to take into account some extra time. CRTs need a so-called blanking time between the data for two display lines. This time is needed for something similar to a carriage return on a typewriter: The electron beam needs to be returned to the start of the next line. Additionally, some extra time is needed to transmit information about the border area around the real picture. About 25% of the bandwidth is used for these additional data. [2]

This means, that there is no specific ThinkPad problem with the throughput - you are just trying to transfer video data at a rate that is outside the specs of DVI. Maybe the DVI transmitter inside the ThinkPad even works at this data rate. But the DVI receiver inside the monitor might be "overclocked".

TFTs don't really need extra time. So there is a chance of writing a display driver with a reduced blanking time. This might explain, why some people were successful with other drivers.

The effective maximum resolution for single link DVI should be around 1600x1200 @ 65 Hz. Has anyone solved his problems by lowering the vertical frequency?

--137.226.40.2 14:23, 1 Mar 2005 (CET)