GeForce Go 6800 Ultra: Powering the Dell Inspirion XPS Gen 2
 

Back when we first took a look at the NVIDIA GeForce Go 6800 we mentioned that NVIDIA was able to run their part at much higher 450/600 clock speeds (the part we tested was running at 300/300). It was much easier for OEMs to drop graphics solutions into existing designs DTR designs using the Pentium 4 and GDDR1 RAM for the video card. Using the hot Pentium 4, much of the Thermal Design Power (TDP), the limit on how much power can be dissipated as heat, is taken up by things other than the graphics core. DDR1 also runs hotter than DDR3, and thus memory clocks are also limited by the thermal restrictions.

http://www.anandtech.com/video/showdoc.aspx?i=2356

//Quicker then a desktop 6800 Ultra ! :o