i have an intel gma900 on a toshiba m45-s331.It apparently works doom 3 but has a lot of lag.I alt+tab'd to find that it used up most of my memory and nearly 100% of my cpu.The ram is currently at 512 - 128( shared mem used my the intel chip).Will upgrading to 1gb - single slot bring smooth game play?? - the graphics are just fine now but the game plays very slowly.Is my cpu working at 100% going to cause problems???
The Intel GMA900 is an integrated graphics card widely sold with Intel motherboard technology.
This particular card does not have it's own dedicated memory, and so has to rely on the system memory for its graphics needs. This undoubtly puts additional strain on your system, since all other IO devices are sharing your system bus with the graphics card. In adddition, more system memory is allocated to your graphics card. For Doom3 you should use at least 1GB of system memory in addition to about at least 128MB dedicated graphics memory.
Besides, PCIx has about 4GB/s maximum bandwith between the GPU and system memory. In comparison, a GeForce 6800 card has over 30GB/s bandwith between it's GPU and dedicated graphics memory. But, it is significantly cheaper to design a system with an integrated graphics card that shares system memory (afterall.. the hope is that the system bus in the future will be able to handle such graphics cards that do not have their own memory). At the moment, this particular hardware setup is ok for playing some new games, but not graphic intensive games such as DOOM3 and/or Far Cry, for example.
Upgrading to 1GB... I would not expect smooth game play with your current setup.
You can try to close all applications except for Doom3. This will help to free up resources and prevent translation to virtual memory. Also, try running the game on a lower setting, and if possible increase your system bus.
Upgrading to 1gb will help. I doubt it will ever bring gameplay up to "smooth", however. But smooth enough might be 25-30fps, which it may give you.
If you could add an AGP or PCI-Express video card (see if your mobo has a slot for it) it would help more than upgrading to 1gb (up to 60 or more fps, depending on the card you buy). Then upgrading to 1gb will help more.