I've tested two of these Startech DP2VGAHD20 adapters/transcoders and the best I can get out of them on my FW900 is a pixel clock of 320 MHz with a max resolution of 1920x1200 @ 95 Hz. Not the reported 375 MHz. Still great, and better than my super expensive HDFury X3 HDMI to VGA adapter ($200) that has a max pixel clock of 225 MHz at a resolution of 1920x1200 @ 60 Hz.
what resolutions did you try to asume that 320mhz limit? i ask because at 1920x1200 the max you will be able to get with the fw900 is 96hz (323mhz) but that limit in this case is because of fw900 horizontal scan limit, not adapter pixel clock limit.
what happens if you try something like 2560x1600@63hz? which is arround 367mhz, or the same at 64hz? (373mhz)
3dfan does have a point. With the tests that I did at 1920 x 1200 with that Startech, 97Hz (325Mhz pixel clock) was out of the FW900's range, but I was able to get 96Hz Viewable (322Mhz pixel clock) and under. At 2304 x 1440 I was able to get 78Hz Viewable (372Mhz pixel clock). Above 78Hz at 2304 x 1440 the Startech started giving me snow. When I had an analog video card, I was able to push the FW900 to 2304 x 1440 at 80Hz, but the adapter obviously can't handle that. I wanted a higher refresh rate than 78Hz. So I settled for 2235 x 1397 (3% of 2304 x 1440) at 83Hz (375Mhz pixel clock).
So it is a fine balance between what the adapter can support to the limitations of our FW900s. People think I am a weirdo for wanting 83Hz and running that oddball resolution, but everyone's eyes are different, and I can totally tell the difference from running 78Hz to 83Hz. I always get asked why I am running that weirdo resolution. So I figured I'd just get that out of the way LOL.