2. 915GM Vs. 855GME, Continued

Like its predecessor, the 915GM uses part of its RAM for video memory. In the 915GM's case, demands by applications are allocated dynamically, with up to 224 MB of the system memory allotted to process image data. Intel calls this technology Digital Video Memory Technology, or DVMT for short. In extremely simplified terms, the GMA900 driver appears to the OS as an application that demands dynamic memory from Windows on behalf of the actual 3D application, such as a game, and releases it again when it's no longer required. As the system and the graphics both share the same memory, just the increased effort involved in administering a shared memory graphics subsystem such as the one in the 915GM will always make it slower than a dedicated graphics chip and additional graphics memory. This represents the well-known compromise between performance and the lowest system cost.

Unlike the 855GME, though, the 915GM supports fast DDR2 memory, provided that the notebook maker allows for this. Not only that, but optional dual-channel operation, in connection with the higher clock speeds of DDR2 memory, result in a purely theoretical increase in memory bandwidth by a factor of 3.3 over the previous model, which only has single-channel operation and DDR333 memory.

All these factors should therefore lead to a noticeable increase in 3D performance - provided that the notebook supports all options offered by the 915GM chipset, as in the case of our Dell Latitude D610 test device.