BFG introduced a new Geforce 9800 GT with a "ThermoIntelligence” passive cooling solution.
BFG Geforce 9800 GT (3)
The BFG Geforce 9800 GT with "ThermoIntelligence” cooling is clocked to 600/1,500/900 MHz (GPU/Shader/VRAM) and has 512 MiByte GDDR3 memory. Thus the passive cooled BFG device doesn't differ from the stock variant in matters of theoretical performance.
BFG uses four heatpipes to transfer the heat of the CPU to the aluminum fins which are placed on the backside of the graphics card. The memory chips aren't cooled separately. For more details see the product page of the BDG Geforce 9800 GT.