Sadly theres a couple things that could contribute to this.
I wonder if it may be due to the GPU itself.
Are you using HDMI?
I remember my HD4890 would sometimes do similar, or at a cold boot if HDMI was used as the output.
No Image on the screen and the GPU fan would spin at 100%.
Sadly, I never did figure out the cause, other than it was due to the HDMI out .. and only occasionally.
Perhaps it was just my card. I never had any issues at all using a DVI output.
Sorry for the generic advice, but it may be something worth looking into.
Also, it could be possible the Sound card is causing some sort of conflict.
Have you double checked you have the latest
drivers for your OS?