Hmm today I tested something which I feared was true... I have a 12cm fan on a zalman bracket these days, blowing on my GTX280 and my SB.
When putting pressure on the SB sink with my finger the temperature goes from 62 to 52 idle... so I guess I have some reseating to do
Probably one of those foam path Asus puts on the sinks that pushes the sink slightly up... I just know I won't be ready in 5 minutes with this.