[Sony Vegas Pro 10] GPU "acceleration" = slower encode?

[DragonQ]

Hi,

I'm rendering a 6 minute 720p25 file using Sony Vegas Pro 10.0c. For some reason if I enable GPU acceleration for Sony AVC, it takes nearly twice as long to encode (7:07 vs 4:11). Whether it's on or off, I only get about 50% CPU usage in total. Is it just because my GPU is rubbish compared to my CPU? I have an i7 920 @ 3.8 GHz and a GTS 250 (1 GB).

I've closed all other programs to ensure nothing else is interfering and I also don't think I'm being bottlenecked by my HDDs because the source and destination locations are on different HDDs and the output currently equates to about 1 MB/s.

[aedipuss]

well to be honest a gts250 is kinda lame for encoding. minimum spec should be like a gts285 or the newer gtx470/gtx570 like adobe cs5 requires.

also are you using different scratch/source/destination hard drives?

[DragonQ]

Yeah that's what I thought.

Always a different source & destination drive, sometimes destination is the same as the scratch drive but not always and it doesn't seem to make a difference to encoding speeds.

[geneaum]

I have a GTX465. I also noticed a speed reduction using GPU processing. Haven't tested with the latest 10c though.