CUDA on headless WHS

I have a headless WHS platform (Windows Server 2003) which I use to encode video using PS3Mediaserver and FFMPEG enabled LAV codec which has been designed to run with CUDA

PS3Mediaserver generates a DLNA video stream for processing through a PS3 to a TV

I have recenetly installed an ASUS GTS450 nvidia card on the WHS to support CUDA processing

If I have a terminal attached to the video card then the LAV CUDA integration works and my Q8400 runs 20% or less

If there is no terminal attached then CUDA does not appear to be active (GPU-z on a RDP session) and the Q8400 peaks at 70% with stuttering on the more demanding video streams

I have recently tried adding a resistive load (3 x 68ohm resistors) to a VGA adapter to simulate a terminal. This ‘dummy’ terminal registers as a second ‘generic analgue device’ when a proper monitor is attached. If I remove the terminal (and leave the VGA simulator) then CUDA does not appear to be active and my CPU loads are still high.

Please advise me how I can enable CUDA processing on a headless WHS using LAV codecs.