Rock Xtreme 770 T7800-8800 - Rock Xtreme 770 T7800-8800


Before we get onto performance, let’s take a look at the technology behind this latest mobile gaming chip. Though it’s based on the same process as the 8800 GT desktop card, it’s important to note it’s not quite as powerful. Whereas the 8800 GT boasts 112 stream processors, the 8800M GTX has 96. It also has a slightly slower core clock speed, lying at 500Mhz rather than 600Mhz. Indeed, these two particular areas put it in line with the 8800 GTS, which shares the same number of stream processors and core clock speed. The 8800M GTX also shares a similar shader clock speed, running at 1.25GHz against the 1.2GHz of the 8800 GTS and 1.5GHz of the 8800 GT.

Another area that sees more compromise is the memory clock speed, which at 1.6GHz is slightly lower than the 1.8GHz of the 8800 GT. However, on the plus side it does retain the 16 ROPs (Raster Operations Units) as the 8800 GT and the 512MB GDDR3 of video memory that runs on a 256-bit memory interface. Thus, despite some compromises, on paper the 8800M GTX ought to be a formidable performer.

It’s a point that’s further illustrated when put against nVidia’s previous leading DX10 graphics part, the 8700M GT. Though it shares the same memory and clock speeds and actually has a slower overall core clock speed, the combination of more stream processors and a better memory interface (256-bit compared to 128-bit) means the 8800M GTX ought to kick the 8700M GT into touch. Memory bandwidth is nearly double that of the 8700M GT at 51GB per second and texture fill rate is over double at 24 billion pixels per second, compared to the paltry 10 billion pixels per second of the 8700M GT.

Moreover, the 8800M GTX should also outperform the best performing DX9 graphics solution, nVidia’s Go 7950 GTX. Though the difference isn’t quite as marked, the 44.9GB per second memory bandwidth and 13.8 billion pixel per second fill rate of the Go 7950 GTX is comfortably beaten by the 8800M GTX. All of which means we might finally see an end to the Go 7950 GTX, which has managed to maintain the notebook graphics performance crown for rather too long. So long and thanks for all the fish.

Aside from all the graphical abilities, the 8800M GTX also shares the video processing acceleration that has become so important among all DX10 graphics solutions. There’s support for H.264, VC-1, MPEG2 and WMV decoding acceleration, while HDCP support allows for the inclusion of the HD DVD drive. Given this and superb screen, watching HD DVDs on the machine is a very pleasurable experience too.

However, HD DVD playback isn’t what we’re really interested in. So, without further ado, it’s time to take a look at how the 8800M GTX performs where it counts: in games!

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